KK> Perhaps significantly, the buttonized (`K b') display of these
KK> sections will show the button areas as
KK>         [1. text/plain] in *bold*
KK>         [2. message/rfc822] in *bold*
KK>         [3. text/plain] in /italic/
KK>         [4. message/rfc822] in *bold*
KK> Shouldn't these be labelled something hierarchical anyway, such as 1., 
KK> 2., 2.1, 2.2, 2.2.1?

It is difficult. The label is used as the argument of
gnus-article-view-part (press 'b').

-- 
Shenghuo ZHU