Having said that, I reiterate my proposal that we make it a new
<sect1> under DDL, before 5.2 Default Values which is the first place in ddl.sgml that assumes you have heard of nulls.
I will go with this and remove the "Data Basics" section I wrote, leaving it to be just a discussion about null values. The tutorial is the only section that really needs unique wording to fit in. No matter where we decide to place it otherwise the core content will be the same, with maybe a different section preface to tie it in.
v3 Attached.
Probably at the 90% complete mark. Minimal index entries, not as thorough a look-about of the existing documentation as I'd like. Probably some wording and style choices to tweak. Figured better to get feedback now before I go into polish mode. In particular, tweaking and re-running the examples.
Yes, I am aware of my improper indentation for programlisting and screen. I wanted to be able to use the code folding features of my editor. Those can be readily un-indented in the final version.
The changes to func.sgml is basically one change repeated something like 20 times with tweaks for true/false. Plus moving the discussion regarding the SQL specification into the new null handling section.
It took me doing this to really understand the difference between row constructors and composite typed values, especially since array constructors produce array typed values and the constructor is just an unimportant implementation option while row constructors introduce meaningfully different behaviors when used.
My plan is to have a v4 out next week, without or without a review of this draft, but then the subsequent few weeks will probably be a bit quiet.