Doc: introduce new layout for tables of functions and operators.

We've long fought with the draconian space limitations of our
traditional table layout for describing SQL functions and operators.
This commit introduces a new approach, though so far I've only applied
it to a few of those tables.  The new way makes use of DocBook's support
for different layouts in different rows of a table, and allows the
descriptions and examples for a function or operator to run to several
lines without as much ugliness and wasted space as before.

The core layout concept is now

     Name              Signature
                      Description
                 Example     Example Result

so that a function or operator really has three table rows not one,
but we group them to look like one row by having the name column
have only one entry for all three rows.  (Actually, there could be
four or more rows if you wanted to have more than one example, which
is another thing that was painful before but works easily now.)
This is handled by a "morerows" annotation on the name entry, which
isn't perfect (notably, the toolchain is not smart enough to avoid
breaking these row groups across PDF pages) but there seems no better
solution in DocBook.  The name column is normally fairly narrow,
allowing plenty of space for the other column(s), and not wasting too
much space when one of the other components runs to multiple lines.

The varying row layout is managed by defining named "spans" and then
tagging entries with a "spanname" of "name", "sig", "desc", "example",
or "exresult".  This provides a bit of semantic annotation to go with
the formatting improvement, which seems like a good thing.  (It seems
that we have to re-define these spans afresh for each table, which is
annoying, but it's not any worse than the duplication involved in
the table headers.  At least that gives us an opportunity to vary the
relative column widths per-table, which is handy since function tables
sometimes need much wider name columns than operator tables.)

Signature entries should be written in the style
    <function>fname</function>(<type>typename</type> ...)
    <returnvalue>typename</returnvalue>
The <returnvalue> tag produces a right arrow before the result type
name.  (I'll document that convention in a user-visible place later.)

While this provides significantly more horizontal space than before
for examples, it's still true that PDF output is a lot narrower than
typical webpage viewing windows, so some examples need to be broken
in places where there is no whitespace.  I've added &zwsp; markers in
suitable places to allow the tables to render warning-free in PDF.

I've so far converted only the date/time operator, date/time function,
and enum function tables in sections 9.9 and 9.10; these were chosen
to provide a reasonable sample of the formatting problems that need
to be solved.  Assuming that this looks good on the website and doesn't
provoke howls of anguish, I'll work on the other similar tables in the
near future.

There's a moderate amount of new editorial content in this patch along
with the raw formatting changes; for instance I had to write text
descriptions for operators that lacked them.  I failed to resist the
temptation to improve some other descriptions and examples, too.

Patch by me, with thanks to Alexander Lakhin for assistance with
figuring out some formatting issues.

Discussion: https://postgr.es/m/9326.1581457869@sss.pgh.pa.us

3 files changed, 711 insertions, 330 deletions

diff --git a/doc/src/sgml/func.sgml b/doc/src/sgml/func.sgml
index 5e5bfddf7c5..7a270eb0ab2 100644
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@@ -6744,127 +6744,256 @@ SELECT regexp_match('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
      <title>Date/Time Operators</title>
 
      <tgroup cols="3">
+      <colspec colname="col1" colwidth="0.25*"/>
+      <colspec colname="col2" colwidth="1*"/>
+      <colspec colname="col3" colwidth="1*"/>
+      <spanspec spanname="name" namest="col1" nameend="col1" align="left"/>
+      <spanspec spanname="sig" namest="col2" nameend="col3" align="left"/>
+      <spanspec spanname="desc" namest="col2" nameend="col3" align="left"/>
+      <spanspec spanname="example" namest="col2" nameend="col2" align="left"/>
+      <spanspec spanname="exresult" namest="col3" nameend="col3" align="left"/>
       <thead>
        <row>
-        <entry>Operator</entry>
-        <entry>Example</entry>
-        <entry>Result</entry>
+        <entry spanname="name" align="center" valign="middle" morerows="2">Operator</entry>
+        <entry spanname="sig" align="center">Signature</entry>
+       </row>
+       <row>
+        <entry spanname="desc" align="center">Description</entry>
+       </row>
+       <row>
+        <entry spanname="example" align="center">Example</entry>
+        <entry spanname="exresult" align="center">Example Result</entry>
        </row>
       </thead>
 
       <tbody>
        <row>
-        <entry> <literal>+</literal> </entry>
-        <entry><literal>date '2001-09-28' + integer '7'</literal></entry>
-        <entry><literal>date '2001-10-05'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>+</literal> </entry>
+        <entry spanname="sig"><type>date</type> <literal>+</literal> <type>integer</type>
+         <returnvalue>date</returnvalue></entry>
        </row>
-
        <row>
-        <entry> <literal>+</literal> </entry>
-        <entry><literal>date '2001-09-28' + interval '1 hour'</literal></entry>
-        <entry><literal>timestamp '2001-09-28 01:00:00'</literal></entry>
+        <entry spanname="desc">Add a number of days to a date</entry>
        </row>
-
        <row>
-        <entry> <literal>+</literal> </entry>
-        <entry><literal>date '2001-09-28' + time '03:00'</literal></entry>
-        <entry><literal>timestamp '2001-09-28 03:00:00'</literal></entry>
+        <entry spanname="example"><literal>date '2001-09-28' + 7</literal></entry>
+        <entry spanname="exresult"><literal>2001-10-05</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>+</literal> </entry>
-        <entry><literal>interval '1 day' + interval '1 hour'</literal></entry>
-        <entry><literal>interval '1 day 01:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>+</literal> </entry>
+        <entry spanname="sig"><type>date</type> <literal>+</literal> <type>interval</type>
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Add an interval to a date</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date '2001-09-28' + interval '1 hour'</literal></entry>
+        <entry spanname="exresult"><literal>2001-09-28 01:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>+</literal> </entry>
-        <entry><literal>timestamp '2001-09-28 01:00' + interval '23 hours'</literal></entry>
-        <entry><literal>timestamp '2001-09-29 00:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>+</literal> </entry>
+        <entry spanname="sig"><type>date</type> <literal>+</literal> <type>time</type>
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Add a time-of-day to a date</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date '2001-09-28' + time '03:00'</literal></entry>
+        <entry spanname="exresult"><literal>2001-09-28 03:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>+</literal> </entry>
-        <entry><literal>time '01:00' + interval '3 hours'</literal></entry>
-        <entry><literal>time '04:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>+</literal> </entry>
+        <entry spanname="sig"><type>interval</type> <literal>+</literal> <type>interval</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Add intervals</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>interval '1 day' + interval '1 hour'</literal></entry>
+        <entry spanname="exresult"><literal>1 day 01:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>- interval '23 hours'</literal></entry>
-        <entry><literal>interval '-23:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>+</literal> </entry>
+        <entry spanname="sig"><type>timestamp</type> <literal>+</literal> <type>interval</type>
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Add an interval to a timestamp</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>timestamp '2001-09-28 01:00' + interval '23 hours'</literal></entry>
+        <entry spanname="exresult"><literal>2001-09-29 00:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>date '2001-10-01' - date '2001-09-28'</literal></entry>
-        <entry><literal>integer '3'</literal> (days)</entry>
+        <entry spanname="name" morerows="2"> <literal>+</literal> </entry>
+        <entry spanname="sig"><type>time</type> <literal>+</literal> <type>interval</type>
+         <returnvalue>time</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Add an interval to a time</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>time '01:00' + interval '3 hours'</literal></entry>
+        <entry spanname="exresult"><literal>04:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>date '2001-10-01' - integer '7'</literal></entry>
-        <entry><literal>date '2001-09-24'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><literal>-</literal> <type>interval</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Negate an interval</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>- interval '23 hours'</literal></entry>
+        <entry spanname="exresult"><literal>-23:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>date '2001-09-28' - interval '1 hour'</literal></entry>
-        <entry><literal>timestamp '2001-09-27 23:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>date</type> <literal>-</literal> <type>date</type>
+         <returnvalue>integer</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract dates</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date '2001-10-01' - date '2001-09-28'</literal></entry>
+        <entry spanname="exresult"><literal>3</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>time '05:00' - time '03:00'</literal></entry>
-        <entry><literal>interval '02:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>date</type> <literal>-</literal> <type>integer</type>
+         <returnvalue>date</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract a number of days from a date</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date '2001-10-01' - 7</literal></entry>
+        <entry spanname="exresult"><literal>2001-09-24</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>time '05:00' - interval '2 hours'</literal></entry>
-        <entry><literal>time '03:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>date</type> <literal>-</literal> <type>interval</type>
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract an interval from a date</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date '2001-09-28' - interval '1 hour'</literal></entry>
+        <entry spanname="exresult"><literal>2001-09-27 23:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>timestamp '2001-09-28 23:00' - interval '23 hours'</literal></entry>
-        <entry><literal>timestamp '2001-09-28 00:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>time</type> <literal>-</literal> <type>time</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract times</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>time '05:00' - time '03:00'</literal></entry>
+        <entry spanname="exresult"><literal>02:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>interval '1 day' - interval '1 hour'</literal></entry>
-        <entry><literal>interval '1 day -01:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>time</type> <literal>-</literal> <type>interval</type>
+         <returnvalue>time</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract an interval from a time</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>time '05:00' - interval '2 hours'</literal></entry>
+        <entry spanname="exresult"><literal>03:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>-</literal> </entry>
-        <entry><literal>timestamp '2001-09-29 03:00' - timestamp '2001-09-27 12:00'</literal></entry>
-        <entry><literal>interval '1 day 15:00:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>timestamp</type> <literal>-</literal> <type>interval</type>
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract an interval from a timestamp</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>timestamp '2001-09-28 23:00' - interval '23 hours'</literal></entry>
+        <entry spanname="exresult"><literal>2001-09-28 00:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>*</literal> </entry>
-        <entry><literal>900 * interval '1 second'</literal></entry>
-        <entry><literal>interval '00:15:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>interval</type> <literal>-</literal> <type>interval</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract intervals</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>interval '1 day' - interval '1 hour'</literal></entry>
+        <entry spanname="exresult"><literal>1 day -01:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>*</literal> </entry>
-        <entry><literal>21 * interval '1 day'</literal></entry>
-        <entry><literal>interval '21 days'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>-</literal> </entry>
+        <entry spanname="sig"><type>timestamp</type> <literal>-</literal> <type>timestamp</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract timestamps</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>timestamp '2001-09-29 03:00' - timestamp '2001-09-27 12:00'</literal></entry>
+        <entry spanname="exresult"><literal>1 day 15:00:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>*</literal> </entry>
-        <entry><literal>double precision '3.5' * interval '1 hour'</literal></entry>
-        <entry><literal>interval '03:30:00'</literal></entry>
+        <entry spanname="name" morerows="4"> <literal>*</literal> </entry>
+        <entry spanname="sig"><type>double precision</type> <literal>*</literal> <type>interval</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Multiply an interval by a scalar</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>900 * interval '1 second'</literal></entry>
+        <entry spanname="exresult"><literal>00:15:00</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>21 * interval '1 day'</literal></entry>
+        <entry spanname="exresult"><literal>21 days</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>3.5 * interval '1 hour'</literal></entry>
+        <entry spanname="exresult"><literal>03:30:00</literal></entry>
        </row>
 
        <row>
-        <entry> <literal>/</literal> </entry>
-        <entry><literal>interval '1 hour' / double precision '1.5'</literal></entry>
-        <entry><literal>interval '00:40:00'</literal></entry>
+        <entry spanname="name" morerows="2"> <literal>/</literal> </entry>
+        <entry spanname="sig"><type>interval</type> <literal>/</literal> <type>double precision</type>
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Divide an interval by a scalar</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>interval '1 hour' / 1.5</literal></entry>
+        <entry spanname="exresult"><literal>00:40:00</literal></entry>
        </row>
       </tbody>
      </tgroup>
@@ -6872,471 +7001,677 @@ SELECT regexp_match('abc01234xyz', '(?:(.*?)(\d+)(.*)){1,1}');
 
     <table id="functions-datetime-table">
      <title>Date/Time Functions</title>
-     <tgroup cols="5">
+     <tgroup cols="3">
+      <colspec colname="col1" colwidth="1*"/>
+      <colspec colname="col2" colwidth="1*"/>
+      <colspec colname="col3" colwidth="1*"/>
+      <spanspec spanname="name" namest="col1" nameend="col1" align="left"/>
+      <spanspec spanname="sig" namest="col2" nameend="col3" align="left"/>
+      <spanspec spanname="desc" namest="col2" nameend="col3" align="left"/>
+      <spanspec spanname="example" namest="col2" nameend="col2" align="left"/>
+      <spanspec spanname="exresult" namest="col3" nameend="col3" align="left"/>
       <thead>
        <row>
-        <entry>Function</entry>
-        <entry>Return Type</entry>
-        <entry>Description</entry>
-        <entry>Example</entry>
-        <entry>Result</entry>
+        <entry spanname="name" align="center" valign="middle" morerows="2">Function</entry>
+        <entry spanname="sig" align="center">Signature</entry>
+       </row>
+       <row>
+        <entry spanname="desc" align="center">Description</entry>
+       </row>
+       <row>
+        <entry spanname="example" align="center">Example</entry>
+        <entry spanname="exresult" align="center">Example Result</entry>
        </row>
       </thead>
 
       <tbody>
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>age</primary>
          </indexterm>
-         <literal><function>age(<type>timestamp</type>, <type>timestamp</type>)</function></literal>
+         <function>age</function>
         </entry>
-        <entry><type>interval</type></entry>
-        <entry>Subtract arguments, producing a <quote>symbolic</quote> result that
+        <entry spanname="sig"><function>age</function>(<type>timestamp</type>, <type>timestamp</type>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract arguments, producing a <quote>symbolic</quote> result that
         uses years and months, rather than just days</entry>
-        <entry><literal>age(timestamp '2001-04-10', timestamp '1957-06-13')</literal></entry>
-        <entry><literal>43 years 9 mons 27 days</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>age(timestamp '2001-04-10', timestamp '1957-06-13')</literal></entry>
+        <entry spanname="exresult"><literal>43 years 9 mons 27 days</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>age(<type>timestamp</type>)</function></literal></entry>
-        <entry><type>interval</type></entry>
-        <entry>Subtract from <function>current_date</function> (at midnight)</entry>
-        <entry><literal>age(timestamp '1957-06-13')</literal></entry>
-        <entry><literal>43 years 8 mons 3 days</literal></entry>
+        <entry spanname="name" morerows="2"><function>age</function></entry>
+        <entry spanname="sig"><function>age</function>(<type>timestamp</type>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Subtract from <function>current_date</function> (at midnight)</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>age(timestamp '1957-06-13')</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>clock_timestamp</primary>
          </indexterm>
-         <literal><function>clock_timestamp()</function></literal>
+         <function>clock_timestamp</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Current date and time (changes during statement execution);
+        <entry spanname="sig"><function>clock_timestamp</function>()
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (changes during statement execution);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>clock_timestamp()</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>current_date</primary>
          </indexterm>
-         <literal><function>current_date</function></literal>
+         <function>current_date</function>
         </entry>
-        <entry><type>date</type></entry>
-        <entry>Current date;
+        <entry spanname="sig"><function>current_date</function>
+         <returnvalue>date</returnvalue></entry>
+       </row>
+       <row>
+         <entry spanname="desc">Current date;
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>current_date</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>current_time</primary>
          </indexterm>
-         <literal><function>current_time</function></literal>
+         <function>current_time</function>
         </entry>
-        <entry><type>time with time zone</type></entry>
-        <entry>Current time of day;
+        <entry spanname="sig"><function>current_time</function>
+         <returnvalue>time with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current time of day;
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>current_time</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2"><function>current_time</function></entry>
+        <entry spanname="sig"><function>current_time</function>(<type>integer</type>)
+         <returnvalue>time with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current time of day, with limited precision;
+         see <xref linkend="functions-datetime-current"/>
+        </entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>current_time(2)</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
+       </row>
+
+       <row>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>current_timestamp</primary>
          </indexterm>
-         <literal><function>current_timestamp</function></literal>
+         <function>current_timestamp</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Current date and time (start of current transaction);
+        <entry spanname="sig"><function>current_timestamp</function>
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current transaction);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>current_timestamp</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2"><function>current_timestamp</function></entry>
+        <entry spanname="sig"><function>current_timestamp</function>(<type>integer</type>)
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current transaction), with limited precision;
+         see <xref linkend="functions-datetime-current"/>
+        </entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>current_timestamp(0)</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
+       </row>
+
+       <row>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>date_part</primary>
          </indexterm>
-         <literal><function>date_part(<type>text</type>, <type>timestamp</type>)</function></literal>
+         <function>date_part</function>
         </entry>
-        <entry><type>double precision</type></entry>
-        <entry>Get subfield (equivalent to <function>extract</function>);
+        <entry spanname="sig"><function>date_part</function>(<type>text</type>, <type>timestamp</type>)
+         <returnvalue>double precision</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Get timestamp subfield (equivalent to <function>extract</function>);
          see <xref linkend="functions-datetime-extract"/>
         </entry>
-        <entry><literal>date_part('hour', timestamp '2001-02-16 20:38:40')</literal></entry>
-        <entry><literal>20</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date_part('hour', timestamp '2001-02-16 20:38:40')</literal></entry>
+        <entry spanname="exresult"><literal>20</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>date_part(<type>text</type>, <type>interval</type>)</function></literal></entry>
-        <entry><type>double precision</type></entry>
-        <entry>Get subfield (equivalent to
+        <entry spanname="name" morerows="2"><function>date_part</function></entry>
+        <entry spanname="sig"><function>date_part</function>(<type>text</type>, <type>interval</type>)
+         <returnvalue>double precision</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Get interval subfield (equivalent to
          <function>extract</function>); see <xref linkend="functions-datetime-extract"/>
         </entry>
-        <entry><literal>date_part('month', interval '2 years 3 months')</literal></entry>
-        <entry><literal>3</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date_part('month', interval '2 years 3 months')</literal></entry>
+        <entry spanname="exresult"><literal>3</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>date_trunc</primary>
          </indexterm>
-         <literal><function>date_trunc(<type>text</type>, <type>timestamp</type>)</function></literal>
+         <function>date_trunc</function>
         </entry>
-        <entry><type>timestamp</type></entry>
-        <entry>Truncate to specified precision; see <xref linkend="functions-datetime-trunc"/>
+        <entry spanname="sig"><function>date_trunc</function>(<type>text</type>, <type>timestamp</type>)
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Truncate to specified precision; see <xref linkend="functions-datetime-trunc"/>
         </entry>
-        <entry><literal>date_trunc('hour', timestamp '2001-02-16 20:38:40')</literal></entry>
-        <entry><literal>2001-02-16 20:00:00</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date_trunc('hour', timestamp '2001-02-16 20:38:40')</literal></entry>
+        <entry spanname="exresult"><literal>2001-02-16 20:00:00</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>date_trunc(<type>text</type>, <type>timestamp with time zone</type>, <type>text</type>)</function></literal></entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Truncate to specified precision in the specified time zone; see <xref linkend="functions-datetime-trunc"/>
+        <entry spanname="name" morerows="2"><function>date_trunc</function></entry>
+        <entry spanname="sig"><function>date_trunc</function>(<type>text</type>, <type>timestamp with time zone</type>, <type>text</type>)
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Truncate to specified precision in the specified time zone; see <xref linkend="functions-datetime-trunc"/>
         </entry>
-        <entry><literal>date_trunc('day', timestamptz '2001-02-16 20:38:40+00', 'Australia/Sydney')</literal></entry>
-        <entry><literal>2001-02-16 13:00:00+00</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date_trunc('day', timestamptz '2001-02-16 20:38:40+00', 'Australia/Sydney')</literal></entry>
+        <entry spanname="exresult"><literal>2001-02-16 13:00:00+00</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>date_trunc(<type>text</type>, <type>interval</type>)</function></literal></entry>
-        <entry><type>interval</type></entry>
-        <entry>Truncate to specified precision; see <xref linkend="functions-datetime-trunc"/>
+        <entry spanname="name" morerows="2"><function>date_trunc</function></entry>
+        <entry spanname="sig"><function>date_trunc</function>(<type>text</type>, <type>interval</type>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Truncate to specified precision; see <xref linkend="functions-datetime-trunc"/>
         </entry>
-        <entry><literal>date_trunc('hour', interval '2 days 3 hours 40 minutes')</literal></entry>
-        <entry><literal>2 days 03:00:00</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>date_trunc('hour', interval '2 days 3 hours 40 minutes')</literal></entry>
+        <entry spanname="exresult"><literal>2 days 03:00:00</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>extract</primary>
          </indexterm>
-         <literal><function>extract</function>(<parameter>field</parameter> from
-         <type>timestamp</type>)</literal>
+         <function>extract</function>
         </entry>
-        <entry><type>double precision</type></entry>
-        <entry>Get subfield; see <xref linkend="functions-datetime-extract"/>
+        <entry spanname="sig"><function>extract</function>(<parameter>field</parameter> <literal>from</literal> <type>timestamp</type>)
+         <returnvalue>double precision</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Get timestamp subfield; see <xref linkend="functions-datetime-extract"/>
         </entry>
-        <entry><literal>extract(hour from timestamp '2001-02-16 20:38:40')</literal></entry>
-        <entry><literal>20</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>extract(hour from timestamp '2001-02-16 20:38:40')</literal></entry>
+        <entry spanname="exresult"><literal>20</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>extract</function>(<parameter>field</parameter> from
-         <type>interval</type>)</literal></entry>
-        <entry><type>double precision</type></entry>
-        <entry>Get subfield; see <xref linkend="functions-datetime-extract"/>
+        <entry spanname="name" morerows="2"><function>extract</function></entry>
+        <entry spanname="sig"><function>extract</function>(<parameter>field</parameter> <literal>from</literal> <type>interval</type>)
+         <returnvalue>double precision</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Get interval subfield; see <xref linkend="functions-datetime-extract"/>
         </entry>
-        <entry><literal>extract(month from interval '2 years 3 months')</literal></entry>
-        <entry><literal>3</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>extract(month from interval '2 years 3 months')</literal></entry>
+        <entry spanname="exresult"><literal>3</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>isfinite</primary>
          </indexterm>
-         <literal><function>isfinite(<type>date</type>)</function></literal>
+         <function>isfinite</function>
         </entry>
-        <entry><type>boolean</type></entry>
-        <entry>Test for finite date (not +/-infinity)</entry>
-        <entry><literal>isfinite(date '2001-02-16')</literal></entry>
-        <entry><literal>true</literal></entry>
+        <entry spanname="sig"><function>isfinite</function>(<type>date</type>)
+         <returnvalue>boolean</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Test for finite date (not +/-infinity)</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>isfinite(date '2001-02-16')</literal></entry>
+        <entry spanname="exresult"><literal>true</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>isfinite(<type>timestamp</type>)</function></literal></entry>
-        <entry><type>boolean</type></entry>
-        <entry>Test for finite time stamp (not +/-infinity)</entry>
-        <entry><literal>isfinite(timestamp '2001-02-16 21:28:30')</literal></entry>
-        <entry><literal>true</literal></entry>
+        <entry spanname="name" morerows="2"><function>isfinite</function></entry>
+        <entry spanname="sig"><function>isfinite</function>(<type>timestamp</type>)
+         <returnvalue>boolean</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Test for finite timestamp (not +/-infinity)</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>isfinite(timestamp 'infinity')</literal></entry>
+        <entry spanname="exresult"><literal>false</literal></entry>
        </row>
 
        <row>
-        <entry><literal><function>isfinite(<type>interval</type>)</function></literal></entry>
-        <entry><type>boolean</type></entry>
-        <entry>Test for finite interval</entry>
-        <entry><literal>isfinite(interval '4 hours')</literal></entry>
-        <entry><literal>true</literal></entry>
+        <entry spanname="name" morerows="2"><function>isfinite</function></entry>
+        <entry spanname="sig"><function>isfinite</function>(<type>interval</type>)
+         <returnvalue>boolean</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Test for finite interval (currently always true)</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>isfinite(interval '4 hours')</literal></entry>
+        <entry spanname="exresult"><literal>true</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>justify_days</primary>
          </indexterm>
-         <literal><function>justify_days(<type>interval</type>)</function></literal>
+         <function>justify_days</function>
         </entry>
-        <entry><type>interval</type></entry>
-        <entry>Adjust interval so 30-day time periods are represented as months</entry>
-        <entry><literal>justify_days(interval '35 days')</literal></entry>
-        <entry><literal>1 mon 5 days</literal></entry>
+        <entry spanname="sig"><function>justify_days</function>(<type>interval</type>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Adjust interval so 30-day time periods are represented as months</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>justify_days(interval '35 days')</literal></entry>
+        <entry spanname="exresult"><literal>1 mon 5 days</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>justify_hours</primary>
          </indexterm>
-         <literal><function>justify_hours(<type>interval</type>)</function></literal>
+         <function>justify_hours</function>
         </entry>
-        <entry><type>interval</type></entry>
-        <entry>Adjust interval so 24-hour time periods are represented as days</entry>
-        <entry><literal>justify_hours(interval '27 hours')</literal></entry>
-        <entry><literal>1 day 03:00:00</literal></entry>
+        <entry spanname="sig"><function>justify_hours</function>(<type>interval</type>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Adjust interval so 24-hour time periods are represented as days</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>justify_hours(&zwsp;interval '27 hours')</literal></entry>
+        <entry spanname="exresult"><literal>1 day 03:00:00</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>justify_interval</primary>
          </indexterm>
-         <literal><function>justify_interval(<type>interval</type>)</function></literal>
+         <function>justify_interval</function>
         </entry>
-        <entry><type>interval</type></entry>
-        <entry>Adjust interval using <function>justify_days</function> and <function>justify_hours</function>, with additional sign adjustments</entry>
-        <entry><literal>justify_interval(interval '1 mon -1 hour')</literal></entry>
-        <entry><literal>29 days 23:00:00</literal></entry>
+        <entry spanname="sig"><function>justify_interval</function>(<type>interval</type>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Adjust interval using <function>justify_days</function> and <function>justify_hours</function>, with additional sign adjustments</entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>justify_interval(&zwsp;interval '1 mon -1 hour')</literal></entry>
+        <entry spanname="exresult"><literal>29 days 23:00:00</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>localtime</primary>
          </indexterm>
-         <literal><function>localtime</function></literal>
+         <function>localtime</function>
         </entry>
-        <entry><type>time</type></entry>
-        <entry>Current time of day;
+        <entry spanname="sig"><function>localtime</function>
+         <returnvalue>time</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current time of day;
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>localtime</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2"><function>localtime</function></entry>
+        <entry spanname="sig"><function>localtime</function>(<type>integer</type>)
+         <returnvalue>time</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current time of day, with limited precision;
+         see <xref linkend="functions-datetime-current"/>
+        </entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>localtime(0)</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
+       </row>
+
+       <row>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>localtimestamp</primary>
          </indexterm>
-         <literal><function>localtimestamp</function></literal>
+         <function>localtimestamp</function>
         </entry>
-        <entry><type>timestamp</type></entry>
-        <entry>Current date and time (start of current transaction);
+        <entry spanname="sig"><function>localtimestamp</function>
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current transaction);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>localtimestamp</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2"><function>localtimestamp</function></entry>
+        <entry spanname="sig"><function>localtimestamp</function>(<type>integer</type>)
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current
+         transaction), with limited precision;
+         see <xref linkend="functions-datetime-current"/>
+        </entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>localtimestamp(2)</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
+       </row>
+
+       <row>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>make_date</primary>
          </indexterm>
-         <literal>
-            <function>
-             make_date(<parameter>year</parameter> <type>int</type>,
-             <parameter>month</parameter> <type>int</type>,
-             <parameter>day</parameter> <type>int</type>)
-            </function>
-         </literal>
+         <function>make_date</function>
         </entry>
-        <entry><type>date</type></entry>
-        <entry>
+        <entry spanname="sig"><function>make_date</function>(<parameter>year</parameter> <type>int</type>,
+         <parameter>month</parameter> <type>int</type>,
+         <parameter>day</parameter> <type>int</type>)
+         <returnvalue>date</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">
          Create date from year, month and day fields
         </entry>
-        <entry><literal>make_date(2013, 7, 15)</literal></entry>
-        <entry><literal>2013-07-15</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>make_date(2013, 7, 15)</literal></entry>
+        <entry spanname="exresult"><literal>2013-07-15</literal></entry>
        </row>
 
        <row>
-        <entry>
-         <indexterm>
+        <entry spanname="name" morerows="2"><indexterm>
           <primary>make_interval</primary>
          </indexterm>
-         <literal>
-          <function>
-           make_interval(<parameter>years</parameter> <type>int</type> DEFAULT 0,
-           <parameter>months</parameter> <type>int</type> DEFAULT 0,
-           <parameter>weeks</parameter> <type>int</type> DEFAULT 0,
-           <parameter>days</parameter> <type>int</type> DEFAULT 0,
-           <parameter>hours</parameter> <type>int</type> DEFAULT 0,
-           <parameter>mins</parameter> <type>int</type> DEFAULT 0,
-           <parameter>secs</parameter> <type>double precision</type> DEFAULT 0.0)
-          </function>
-         </literal>
+         <function>make_interval</function>
         </entry>
-        <entry><type>interval</type></entry>
-        <entry>
+        <entry spanname="sig"><function>make_interval</function>(<optional> <parameter>year</parameter> <type>int</type>
+         <optional>, <parameter>month</parameter> <type>int</type>
+         <optional>, <parameter>week</parameter> <type>int</type>
+         <optional>, <parameter>day</parameter> <type>int</type>
+         <optional>, <parameter>hour</parameter> <type>int</type>
+         <optional>, <parameter>min</parameter> <type>int</type>
+         <optional>, <parameter>sec</parameter> <type>double precision</type>
+         </optional></optional></optional></optional></optional></optional></optional>)
+         <returnvalue>interval</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">
          Create interval from years, months, weeks, days, hours, minutes and
-         seconds fields
+         seconds fields, each of which can default to zero
         </entry>
-        <entry><literal>make_interval(days =&gt; 10)</literal></entry>
-        <entry><literal>10 days</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>make_interval(days =&gt; 10)</literal></entry>
+        <entry spanname="exresult"><literal>10 days</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>make_time</primary>
          </indexterm>
-         <literal>
-          <function>
-           make_time(<parameter>hour</parameter> <type>int</type>,
-           <parameter>min</parameter> <type>int</type>,
-           <parameter>sec</parameter> <type>double precision</type>)
-          </function>
-         </literal>
+         <function>make_time</function>
         </entry>
-        <entry><type>time</type></entry>
-        <entry>
+        <entry spanname="sig"><function>make_time</function>(<parameter>hour</parameter> <type>int</type>,
+         <parameter>min</parameter> <type>int</type>,
+         <parameter>sec</parameter> <type>double precision</type>)
+         <returnvalue>time</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">
          Create time from hour, minute and seconds fields
         </entry>
-        <entry><literal>make_time(8, 15, 23.5)</literal></entry>
-        <entry><literal>08:15:23.5</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>make_time(8, 15, 23.5)</literal></entry>
+        <entry spanname="exresult"><literal>08:15:23.5</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>make_timestamp</primary>
          </indexterm>
-         <literal>
-          <function>
-           make_timestamp(<parameter>year</parameter> <type>int</type>,
-           <parameter>month</parameter> <type>int</type>,
-           <parameter>day</parameter> <type>int</type>,
-           <parameter>hour</parameter> <type>int</type>,
-           <parameter>min</parameter> <type>int</type>,
-           <parameter>sec</parameter> <type>double precision</type>)
-          </function>
-         </literal>
+         <function>make_timestamp</function>
         </entry>
-        <entry><type>timestamp</type></entry>
-        <entry>
+        <entry spanname="sig"><function>make_timestamp</function>(<parameter>year</parameter> <type>int</type>,
+         <parameter>month</parameter> <type>int</type>,
+         <parameter>day</parameter> <type>int</type>,
+         <parameter>hour</parameter> <type>int</type>,
+         <parameter>min</parameter> <type>int</type>,
+         <parameter>sec</parameter> <type>double precision</type>)
+         <returnvalue>timestamp</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">
          Create timestamp from year, month, day, hour, minute and seconds fields
         </entry>
-        <entry><literal>make_timestamp(2013, 7, 15, 8, 15, 23.5)</literal></entry>
-        <entry><literal>2013-07-15 08:15:23.5</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>make_timestamp(&zwsp;2013, 7, 15, 8, 15, 23.5)</literal></entry>
+        <entry spanname="exresult"><literal>2013-07-15 08:15:23.5</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>make_timestamptz</primary>
          </indexterm>
-         <literal>
-          <function>
-           make_timestamptz(<parameter>year</parameter> <type>int</type>,
-           <parameter>month</parameter> <type>int</type>,
-           <parameter>day</parameter> <type>int</type>,
-           <parameter>hour</parameter> <type>int</type>,
-           <parameter>min</parameter> <type>int</type>,
-           <parameter>sec</parameter> <type>double precision</type>,
-           <optional> <parameter>timezone</parameter> <type>text</type> </optional>)
-          </function>
-         </literal>
+         <function>make_timestamptz</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>
+        <entry spanname="sig"><function>make_timestamptz</function>(<parameter>year</parameter> <type>int</type>,
+         <parameter>month</parameter> <type>int</type>,
+         <parameter>day</parameter> <type>int</type>,
+         <parameter>hour</parameter> <type>int</type>,
+         <parameter>min</parameter> <type>int</type>,
+         <parameter>sec</parameter> <type>double precision</type>
+         <optional>, <parameter>timezone</parameter> <type>text</type> </optional>)
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">
          Create timestamp with time zone from year, month, day, hour, minute
          and seconds fields; if <parameter>timezone</parameter> is not
          specified, the current time zone is used
         </entry>
-        <entry><literal>make_timestamptz(2013, 7, 15, 8, 15, 23.5)</literal></entry>
-        <entry><literal>2013-07-15 08:15:23.5+01</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>make_timestamptz(&zwsp;2013, 7, 15, 8, 15, 23.5)</literal></entry>
+        <entry spanname="exresult"><literal>2013-07-15 08:15:23.5+01</literal></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>now</primary>
          </indexterm>
-         <literal><function>now()</function></literal>
+         <function>now</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Current date and time (start of current transaction);
+        <entry spanname="sig"><function>now</function>()
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current transaction);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>now()</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>statement_timestamp</primary>
          </indexterm>
-         <literal><function>statement_timestamp()</function></literal>
+         <function>statement_timestamp</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Current date and time (start of current statement);
+        <entry spanname="sig"><function>statement_timestamp</function>()
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current statement);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>statement_timestamp()</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>timeofday</primary>
          </indexterm>
-         <literal><function>timeofday()</function></literal>
+         <function>timeofday</function>
         </entry>
-        <entry><type>text</type></entry>
-        <entry>Current date and time
+        <entry spanname="sig"><function>timeofday</function>()
+         <returnvalue>text</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time
          (like <function>clock_timestamp</function>, but as a <type>text</type> string);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>timeofday()</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
        </row>
 
        <row>
-        <entry>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>transaction_timestamp</primary>
          </indexterm>
-         <literal><function>transaction_timestamp()</function></literal>
+         <function>transaction_timestamp</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Current date and time (start of current transaction);
+        <entry spanname="sig"><function>transaction_timestamp</function>()
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Current date and time (start of current transaction);
          see <xref linkend="functions-datetime-current"/>
         </entry>
-        <entry></entry>
-        <entry></entry>
        </row>
        <row>
-        <entry>
+        <entry spanname="example"><literal>transaction_&zwsp;timestamp()</literal></entry>
+        <entry spanname="exresult"><replaceable>variable</replaceable></entry>
+       </row>
+       <row>
+        <entry spanname="name" morerows="2">
          <indexterm>
           <primary>to_timestamp</primary>
          </indexterm>
-         <literal><function>to_timestamp(<type>double precision</type>)</function></literal>
+         <function>to_timestamp</function>
         </entry>
-        <entry><type>timestamp with time zone</type></entry>
-        <entry>Convert Unix epoch (seconds since 1970-01-01 00:00:00+00) to
+        <entry spanname="sig"><function>to_timestamp</function>(<type>double precision</type>)
+         <returnvalue>timestamp with time zone</returnvalue></entry>
+       </row>
+       <row>
+        <entry spanname="desc">Convert Unix epoch (seconds since 1970-01-01 00:00:00+00) to
          timestamp</entry>
-        <entry><literal>to_timestamp(1284352323)</literal></entry>
-        <entry><literal>2010-09-13 04:32:03+00</literal></entry>
+       </row>
+       <row>
+        <entry spanname="example"><literal>to_timestamp(&zwsp;1284352323)</literal></entry>
+        <entry spanname="exresult"><literal>2010-09-13 04:32:03+00</literal></entry>
        </row>
       </tbody>
      </tgroup>
@@ -8310,52 +8645,83 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple
 
   <table id="functions-enum-table">
     <title>Enum Support Functions</title>
-    <tgroup cols="4">
+    <tgroup cols="3">
+     <colspec colname="col1" colwidth="0.5*"/>
+     <colspec colname="col2" colwidth="1*"/>
+     <colspec colname="col3" colwidth="1*"/>
+     <spanspec spanname="name" namest="col1" nameend="col1" align="left"/>
+     <spanspec spanname="sig" namest="col2" nameend="col3" align="left"/>
+     <spanspec spanname="desc" namest="col2" nameend="col3" align="left"/>
+     <spanspec spanname="example" namest="col2" nameend="col2" align="left"/>
+     <spanspec spanname="exresult" namest="col3" nameend="col3" align="left"/>
      <thead>
       <row>
-       <entry>Function</entry>
-       <entry>Description</entry>
-       <entry>Example</entry>
-       <entry>Example Result</entry>
+       <entry spanname="name" align="center" valign="middle" morerows="2">Function</entry>
+       <entry spanname="sig" align="center">Signature</entry>
+      </row>
+      <row>
+       <entry spanname="desc" align="center">Description</entry>
+      </row>
+      <row>
+       <entry spanname="example" align="center">Example</entry>
+       <entry spanname="exresult" align="center">Example Result</entry>
       </row>
      </thead>
      <tbody>
       <row>
-       <entry>
-         <indexterm>
-          <primary>enum_first</primary>
-         </indexterm>
-         <literal>enum_first(anyenum)</literal>
+       <entry spanname="name" morerows="2">
+        <indexterm>
+         <primary>enum_first</primary>
+        </indexterm>
+        <function>enum_first</function>
        </entry>
-       <entry>Returns the first value of the input enum type</entry>
-       <entry><literal>enum_first(null::rainbow)</literal></entry>
-       <entry><literal>red</literal></entry>
+       <entry spanname="sig"><function>enum_first</function>(<type>anyenum</type>) <returnvalue>anyenum</returnvalue></entry>
       </row>
       <row>
-       <entry>
-         <indexterm>
-          <primary>enum_last</primary>
-         </indexterm>
-         <literal>enum_last(anyenum)</literal>
+       <entry spanname="desc">Returns the first value of the input enum type</entry>
+      </row>
+      <row>
+       <entry spanname="example"><literal>enum_first(&zwsp;null::rainbow)</literal></entry>
+       <entry spanname="exresult"><literal>red</literal></entry>
+      </row>
+      <row>
+       <entry spanname="name" morerows="2">
+        <indexterm>
+         <primary>enum_last</primary>
+        </indexterm>
+        <function>enum_last</function>
        </entry>
-       <entry>Returns the last value of the input enum type</entry>
-       <entry><literal>enum_last(null::rainbow)</literal></entry>
-       <entry><literal>purple</literal></entry>
+       <entry spanname="sig"><function>enum_last</function>(<type>anyenum</type>) <returnvalue>anyenum</returnvalue></entry>
       </row>
       <row>
-       <entry>
-         <indexterm>
-          <primary>enum_range</primary>
-         </indexterm>
-         <literal>enum_range(anyenum)</literal>
+       <entry spanname="desc">Returns the last value of the input enum type</entry>
+      </row>
+      <row>
+       <entry spanname="example"><literal>enum_last(&zwsp;null::rainbow)</literal></entry>
+       <entry spanname="exresult"><literal>purple</literal></entry>
+      </row>
+      <row>
+       <entry spanname="name" morerows="2">
+        <indexterm>
+         <primary>enum_range</primary>
+        </indexterm>
+        <function>enum_range</function>
        </entry>
-       <entry>Returns all values of the input enum type in an ordered array</entry>
-       <entry><literal>enum_range(null::rainbow)</literal></entry>
-       <entry><literal>{red,orange,yellow,green,blue,purple}</literal></entry>
+       <entry spanname="sig"><function>enum_range</function>(<type>anyenum</type>) <returnvalue>anyarray</returnvalue></entry>
       </row>
       <row>
-       <entry morerows="2"><literal>enum_range(anyenum, anyenum)</literal></entry>
-       <entry morerows="2">
+       <entry spanname="desc">Returns all values of the input enum type in an ordered array</entry>
+      </row>
+      <row>
+       <entry spanname="example"><literal>enum_range(&zwsp;null::rainbow)</literal></entry>
+       <entry spanname="exresult"><literal>{red,orange,yellow,&zwsp;green,blue,purple}</literal></entry>
+      </row>
+      <row>
+       <entry spanname="name" morerows="4"><function>enum_range</function></entry>
+       <entry spanname="sig"><function>enum_range</function>(<type>anyenum</type>, <type>anyenum</type>) <returnvalue>anyarray</returnvalue></entry>
+      </row>
+      <row>
+       <entry spanname="desc">
         Returns the range between the two given enum values, as an ordered
         array. The values must be from the same enum type. If the first
         parameter is null, the result will start with the first value of
@@ -8363,16 +8729,18 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple
         If the second parameter is null, the result will end with the last
         value of the enum type.
        </entry>
-       <entry><literal>enum_range('orange'::rainbow, 'green'::rainbow)</literal></entry>
-       <entry><literal>{orange,yellow,green}</literal></entry>
       </row>
       <row>
-       <entry><literal>enum_range(NULL, 'green'::rainbow)</literal></entry>
-       <entry><literal>{red,orange,yellow,green}</literal></entry>
+       <entry spanname="example"><literal>enum_range(&zwsp;'orange'::rainbow, 'green'::rainbow)</literal></entry>
+       <entry spanname="exresult"><literal>{orange,yellow,green}</literal></entry>
+      </row>
+      <row>
+       <entry spanname="example"><literal>enum_range(NULL, 'green'::rainbow)</literal></entry>
+       <entry spanname="exresult"><literal>{red,orange,yellow,&zwsp;green}</literal></entry>
       </row>
       <row>
-       <entry><literal>enum_range('orange'::rainbow, NULL)</literal></entry>
-       <entry><literal>{orange,yellow,green,blue,purple}</literal></entry>
+       <entry spanname="example"><literal>enum_range(&zwsp;'orange'::rainbow, NULL)</literal></entry>
+       <entry spanname="exresult"><literal>{orange,yellow,green,&zwsp;blue,purple}</literal></entry>
       </row>
      </tbody>
     </tgroup>
@@ -8384,7 +8752,7 @@ CREATE TYPE rainbow AS ENUM ('red', 'orange', 'yellow', 'green', 'blue', 'purple
     only about its declared data type.  Either null or a specific value of
     the type can be passed, with the same result.  It is more common to
     apply these functions to a table column or function argument than to
-    a hardwired type name as suggested by the examples.
+    a hardwired type name as used in the examples.
    </para>
  </sect1>
 
diff --git a/doc/src/sgml/stylesheet-common.xsl b/doc/src/sgml/stylesheet-common.xsl
index e148c9057f8..a13565e6018 100644
--- a/doc/src/sgml/stylesheet-common.xsl
+++ b/doc/src/sgml/stylesheet-common.xsl
@@ -49,6 +49,12 @@
   <xsl:call-template name="inline.charseq"/>
 </xsl:template>
 
+<!-- Render <returnvalue> with a right arrow then the type name -->
+<xsl:template match="returnvalue">
+  &#x2192;
+  <xsl:call-template name="inline.monoseq"/>
+</xsl:template>
+
 <xsl:template match="structfield">
   <xsl:call-template name="inline.monoseq"/>
 </xsl:template>
diff --git a/doc/src/sgml/stylesheet-fo.xsl b/doc/src/sgml/stylesheet-fo.xsl
index ea754084be0..2aaae82092f 100644
--- a/doc/src/sgml/stylesheet-fo.xsl
+++ b/doc/src/sgml/stylesheet-fo.xsl
@@ -63,6 +63,13 @@
   </fo:inline>
 </xsl:template>
 
+<!-- overrides stylesheet-common.xsl -->
+<!-- FOP needs us to be explicit about the font to use for right arrow -->
+<xsl:template match="returnvalue">
+  <fo:inline font-family="{$symbol.font.family}">&#x2192; </fo:inline>
+  <xsl:call-template name="inline.monoseq"/>
+</xsl:template>
+
 <!-- bug fix from <https://sourceforge.net/p/docbook/bugs/1360/#831b> -->
 
 <xsl:template match="varlistentry/term" mode="xref-to">