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.
Like Snoopy sleeps on?
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?