What were "shadow blocks"?

I vaguely recall a documentation scheme which used something called "shadow blocks". What were they? How were they used? Where can I go to read up on them?

My application has nothing to do with Forth. Something I once read is trying to rise to surface in connection with a documentation problem I'm working on. I'm going on the theory if I read about enough different ways of doing documentation I'll have an AHHSOOOO moment (I can hope can't I ;)

Thanks
.

Relevant Pages

  • Re: What were "shadow blocks"?
    ... trying to rise to surface in connection with a documentation problem I'm ... docs in HTML format. ... that inforces structure and appropriate verbosity. ... have shadow blocks; it is somewhat in contradiction with his ...
    (comp.lang.forth)
  • Re: What were "shadow blocks"?
    ... I'm going on the theory if I read about enough different ways of doing documentation I'll have an AHHSOOOO moment ... Shadow blocks are typically 1,024 bytes of text that document Forth source code. ... Any program written using Pygmy can be built with shadow blocks. ...
    (comp.lang.forth)