I will take another stab at this...
IF "Tags" is your only label.. then maybe that what got every one confused.
These are the possible TWO answers:
1) Assuming you intend to explain what each "tag" is:
<dd> The definition for foo would go here. DD can contain any other tags you need, including DIVs and Ps</dd>
<dd>Alternate definition, if needed</dd>
<dd>Yet another alternate definition, if needed</dd>
<dd> The definion for bar would go here.</dd>
<dd> The definion for etc would go here.</dd>
2) Assuming you DO NOT intend to explain what each tab is:
The really its just a regular old list with a header is the proper semantic to use.
So I guess, my answer to your question is the LABEL of a list in not part of the list. it is in fact a SEPARATE header. Hope I was closer this time.