The following documentation comment has been logged on the website:
Page: https://www.postgresql.org/docs/15/functions-comparisons.html
Description:
In section #FUNCTIONS-COMPARISONS-IN-SCALAR operator IN is described as a
expression for scalars, and as a shorthand notation for a combination of
operators || and =
In section #COMPOSITE-TYPE-COMPARISON described extension, to use operators
with a records, like "record operator record" for uncertain set of
operators, and noted "Composite type comparisons are allowed when the
operator is =, <>, <, <=, > or >=, or has semantics similar to one of
these." and with a some difficult to understand note about B-trees.
And as result, I can't see a direct description for allowance to use a
syntax like a "(key_part_1, key_part_2) IN ( ('B',1), ('C',2) )"
So I propose to mention record types in section
#FUNCTIONS-COMPARISONS-IN-SCALAR. Phrase "The right-hand side is a
parenthesized list of scalar expressions." can be replaced to phrases "The
right-hand side is a parenthesized list of scalar or record expressions.
About records [see further](#COMPOSITE-TYPE-COMPARISON)"
Also I propose make similar adjustments in other sections of this page, and
make cross-links here and in a
https://www.postgresql.org/docs/current/functions-subquery.html page near
the text mentions of each others.