In the Doghouse

One question leads to another . . .

We've determined that at the 4/3, tabs may be used in an appellate appendix if the document still fits into the court's file boxes, or doghouses.

"Doghouse?" 

Like Snoopy sleeps on?

Turns out other courts, not just the 4/3, use the term, to the confusion of people here, and here, and here.  At the Lectern wondered as well, and helpfully included a photo of a California Supreme Court doghouse (right)

  

So there a doghouse is a tied binder, not a magazine file box like the 4/3 uses. 

The question remains, whence "doghouse"?

Mike McKee at the Recorder concedes, "How such files became known as doghouses isn't clear."  I haven't been able to find out, either.  The OED states the term is used to refer generally to anything shaped like the pitched roof of Snoopy's home. 

Like an open binder?