I'd ping Jeff and ask him.  He's the sole code contributor.

what's his username?

It can't truly be called open source if it's restricted!

THAT is a very true statement.
I'd ping Jeff and ask him.  He's the sole code contributor.  I have access but I don't contribute anything to the code. 
Be careful what you ask for, Jeff refers to the codebase as a jumbled steaming pile of spaghetti code.

  There are many differing subsets of "open-source" software for instance, such as "BeerWare"? 
Mmmm.  "BeerWare"; D'OH!!!

Is it a " Creative Commons License"?
http://creativecommons.org/licenses/by/3.0/
There are license model that are even good for commercial use.

Answer:  Not necessarily.  If i remember correctly, a variety of that license model allows an author to charge a "nominal" fee.  Once again, if i'm wrong about that, then somebody should correct me.

I could probably only barely guess the total number of man-hours DP_BASE represents, considering development.

Edit:  see "Common Misunderstandings of “Free Software” and “Open Source”"
          http://www.gnu.org/philosophy/open-sour … point.html

Though access to the repositories is restricted to members of the "code team".

It can't truly be called open source if it's restricted!

I don't suppose I'd be allowed a temporary membership to the "code team"?

I'd like to help (I have some VB experience) if I can.