Accessibility tagging FrameMaker to PDF

[quills at airmail.net]

I am beset with a particularly clueless implementation of 
Accessibility requirements. The company I work for is required to 
support Section 508, yet the instructions they have produced are 
basically waving their hands over the subject without concrete 
guidelines. So I'm having to define these as I go.

My question is: When tagging the paragraph tags for Accessibility, 
what kind of hierarchy detail is necessary?

For instance, do I set a descending hierarchy from the heading tags 
down to the body text, and lump all of the body text, tables, bullets 
etc. under the same tag level? Or do I follow the structure of the 
document strictly, separating the body text from levels of bullets, 
steps, tables, etc?

Is there a difference in how the document behaves if I have a large 
set of granularity, or if it flattens after I tag the headings?

Scott