@@ -340,17 +340,23 @@ A comment beginning with "/*" extends to the first occurrence of "*/".
340340 <title>Names</title>
341341
342342 <para>
343- Names in SQL are sequences of less than NAMEDATALEN alphanumeric characters,
344- starting with an alphabetic character. By default, NAMEDATALEN is set
345- to 32 (but at the time the system is built, NAMEDATALEN can be changed
346- by changing the <literal>#define</literal> in
347- src/backend/include/postgres.h).
348- Underscore ("_") is considered an alphabetic character.
343+ Names in SQL must begin with a letter
344+ (<literal>a</literal>-<literal>z</literal>) or underscore
345+ (<literal>_</literal>).
346+ Subsequent characters in a name can be letters, digits
347+ (<literal>0</literal>-<literal>9</literal>),
348+ or underscores. The system uses no more than NAMEDATALEN-1 characters
349+ of a name; longer names can be written in queries, but they will be
350+ truncated.
351+ By default, NAMEDATALEN is 32 so the maximum name length is 31 (but
352+ at the time the system is built, NAMEDATALEN can be changed in
353+ src/include/postgres_ext.h).
349354 </para>
350355
351356 <para>
352357 Names containing other characters may be formed by surrounding them
353- with double quotes. For example, table or column names may contain
358+ with double quotes (<literal>"</literal>). For example, table or column
359+ names may contain
354360 otherwise disallowed characters such as spaces, ampersands, etc. if
355361 quoted. Quoting a name also makes it case-sensitive,
356362 whereas unquoted names are always folded to lower case. For example,
@@ -359,6 +365,12 @@ A comment beginning with "/*" extends to the first occurrence of "*/".
359365 considered the same by <productname>Postgres</productname>, but
360366 <literal>"Foo"</literal> is a different name.
361367 </para>
368+
369+ <para>
370+ Double quotes can also be used to protect a name that would otherwise
371+ be taken to be an SQL keyword. For example, <literal>IN</literal>
372+ is a keyword but <literal>"IN"</literal> is a name.
373+ </para>
362374 </sect1>
363375
364376 <sect1>