Adrian Klaver-4 wrote > I will leave it to philosophers to decide whether NULL is empty, but it > seems the documentation could be more explicit on what constitutes empty > in the text versus constructor method of creating a range. Would it be sufficient to simply add another paragraph: "The lower-bound may be either a string that is valid input for the subtype, or NULL to indicate no lower bound. Likewise, upper-bound may be either a string that is valid input for the subtype, or NULL to indicate no upper bound." ? @ 8.17.6. Constructing Ranges I'm not particularly enamored with the title since "Range Input" is a means of "Constructing [a] Range"...incorporating the word function into that would seem warranted. How about: 8.17.6 Functional Range Construction ? For 8.17.5 The concept of "Input/Output" implies that we are dealing with string-like literals and while not something an absolute beginner might pick up on is likely sufficient and thus omitting the word "Literal" is OK by me. All that said it is taken for granted that you cannot have an empty function argument so ('val',) is invalid on its face. The question becomes whether you should use ('val','') or ('val',NULL). The only place that is answered is a single example. It should be in the body of the text too. David J. -- View this message in context: http://postgresql.nabble.com/Range-type-bounds-tp5828396p5828402.html Sent from the PostgreSQL - general mailing list archive at Nabble.com. -- Sent via pgsql-general mailing list (pgsql-general@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general