DOCBOOK: Which attribute to use for context-sensitive help?

[Tom dot Slee at sybase dot com]

Dear docbookers,

I am trying to build context-sensitive help linking into a docbook document
and have to make a decision about which attribute to use to hold the
context ID. I'm sure others will have done this before, and am looking for
advice on an "appropriate" choice of attribute.

The application calls the help system, supplying a context ID, which is
mapped to an element in the document. I want to store this mapping in the
document, and then we can write out what the help system needs. I'd like to
assign the context ID for an element to an attribute for that element. I
could use any old attribute, such as "role"

<sect1 id="a-helpful-topic" role="SOME-HELP-CONTEXT-ID">...

My question is, there is no obvious attribute to use for this purpose. Is
there a conventional choice that I can follow?

Tom