Where is the headers object as used in accordion declared?

Where is the headers object as used in accordion declared?

Greetings all,
 
Simply put, I'm trying to roll some new accordion functionality involving things such as a headerless accordion (maybe even extensible to an accordion grid), and a horrizontal accordion.
 
I'm new to developing for jquery ui so I'm modifying the existing accordion for the headerless kind, even though much of the mutually exclusive design and functionality make it a separate widget. Since I won't have headers in a headerless accordion, either removing or renaming the headers object seems the most sensible thing to do if it is not something more global that is being accessed in other files. Throughout jquery.ui.accordion.js, the this.headers object is assigned and used as a list of the headers preceding each content panel, but the trouble is that I can't find where the headers object is declared.
 
So, as the question is titled, where is headers declared? I've searched for some time and am feeling rather embarassed for having to ask, but, as I'm rather new here and am turning up nothing, I would appreciate any help.
 
Thanks in advance.