Hi Aaron,
I found reference to this on page 91 of the pdf below
http://www.adobe.com/devnet/pdf/pdfs/xfa_spec_2_4.pdfHere's a snipit
Explicit naming is available as an option in the Data DOM. However, in the Data DOM, the element tag is taken as the name by default, but may be overridden by the content of an attribute. Thus, nodes in the Data DOM always have names, one way or the other. See the XFA Names on page 70 for a description of the explicit naming option and how to invoke it. Consequently the "#" syntax is not usually needed for nodes in the Data DOM. One case in which it is needed is when the element tag contains characters that are not allowed in the names of objects by the scripting language. For example, FormCalc does not support object names containing a minus ("-") character. If such an element is loaded into the Data DOM without mapping the name to something else (another load option), the resulting dataGroup or
dataValue object cannot be referenced using the usual syntax. In such a case, it is necessary to use #dataGroup or #dataValue, respectively.
Hope this helps.
Pam