We've done a good job of making it easy in Schema 1.1 Part 2 to jump from the table of contents to descriptions of particular types like Integer.  Abstractions like "List" and "Union" seem equally important, but you have to more or less guess that they'd be in the section "2.4 Datatype Distinctions".

I can imagine serveral potential resolutions to this concern, any of which would be agreeable to me:

a) Add at least section 2.4.1 to the TOC.   The obvious thing to do would be to also add 2.4.2 Special vs. Primitive vs. Ordinary Datatypes; 2.4.3 Definition, Derivation, Restriction, and Construction; 2.4.4 Built-in vs. User-Defined Datatypes

b) Rearrange the sections in 2.4 so that "list" and "union" (and perhaps Atomic as well) are level 3 rather than level 4 headings, and then include them individually.  They seem like quite important abstractions in the type system, and they're buried quite deeply in the TOC hierarchy.

Other solutions might be agreeable to me too, but I strongly feel we should do something better than what we currently have.

Noah