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?

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?