[Oberon] "built in" functions

[shark at gulfnet.sd64.bc.ca]

I want to understand the "built in" functions
(if that is the correct terminology) better.
CAP( ) for example.  Appears it is defined in 
OPB.Mod.  Ie.

			| cap:
					IF f = Char THEN
						IF z^.class = Nconst THEN
							z^.conval^.intval := ORD(CAP(CHR(z^.conval^.intval))); z^.obj := NIL
						ELSE z := NewOp(op, typ, z)
						END
					ELSE err(111); z^.typ := OPT.chartyp
					END

Can anyone shed a little light on this?  
With ORD(CAP(CHR(z^.conval^.intval))) 
present, how is this not a recursive definition?

Thanks,     ... Peter E.




Desktops.OpenDoc  http://carnot.pathology.ubc.ca/