(b)trim anomalies

I was just wondering why the btrim syntax that takes only a single
argument is not documented in 9.4 in the documentation (I checked both
7.4 and 8.0 docs).

This is in a 7.4.5 installation:

pg=# \df btrim
List of functions
Result data type | Schema | Name | Argument data types
------------------+------------+-------+---------------------
bytea | pg_catalog | btrim | bytea, bytea
text | pg_catalog | btrim | text
text | pg_catalog | btrim | text, text
(3 rows)

Is it ever documented anywhere that the single-argument version of
btrim can be used to remove whitespace from the left and right of a
given string? Is this version not supposed to be user-facing for some
reason?

Also, in this post:

http://archives.postgresql.org/pgsql-sql/2002-01/msg00053.php

Bruce sort of explains that TRIM is an ANSI word but doesn't fully
explain why it doesn't show up in a \df listing:

pg=# \df trim
List of functions
Result data type | Schema | Name | Argument data types
------------------+--------+------+---------------------
(0 rows)

This one's more a curiosity thing.

-tfo

--
Thomas F. O'Connell
Co-Founder, Information Architect
Sitening, LLC
http://www.sitening.com/
110 30th Avenue North, Suite 6
Nashville, TN 37203-6320
615-260-0005