Roughly speaking, the numbering dislayed by Autonum fields is controlled
by the /Outline level/ of the paragraph (and for the built-in Heading
styles, that is probably determined by the Style itself rather than for
individual paragraphs.
If you go to Format->Paragraph (in Word 2007, Page layout tab->Paragraph
section, and click the small icon at the bottom right to open the full
paragraph dialog box, then Indents and Spacing->Outline level.
Personally, I would avoid AUTONUM fields - if you have a straightforward
numbering requirement in a recent version of Word, it is probably better
to use a multilevel numbered list (as mentioned by PamC), and if you
have to use a field-based approach, an approach based on SEQ fields (as
mentioned by Greg) is probably more reliable (although you do have to
update SEQ fields manually) because you can define all the
characteristics of the numbering in the fields themselves and you do not
have to worry about all your outline levels being correct.
Peter Jamieson
http://tips.pjmsn.me.uk