WIlderness: What is meangin on 'noex = -1'

While it seems clear the 'noex' 0-4 indicates the number of parameters 
expected by the method, it appears that
other things are also encoded.

Can someone interpret what the full usage of this encoding means.
  for example: what does "NOEX" Mean - I pick names like that to 
indicate what I am working with
  for example: Safe level is also at times encoded with 'noex'

Thanks in advance.

PS If I repeat an old question - My Disk went bye-bye and I lost my 
Question Data Base.  I am fixing THAT
 situation now -- (a data base backup nightly outside my Mail System!).

           Chuck