[texhax] need name of variable containing value of documentclass

[Fehd, Ronald J. (CDC/OCOO/ITSO)]

Greetings:

I am using a file in two different documents: 
the first is a stand-alone doc which is a documentclass=article
and, after editing, proofreading, and reviewing, 
I will input that file in a larger doc with documentclass=book.

Q: which macro variable contains the value of documentclass?

I would like to add the chapter command to the beginning of the file
when the doc is being input in the documentclass=book

i.e.:
if documentclass=book {chapter[\docTitleShort]{\docTitle}}

thanks

Ron Fehd  {SAS} macro maven