Subj : Re: Updated API ref
To   : netscape.public.mozilla.jseng
From : Jens Thiele
Date : Thu Apr 22 2004 01:06 pm

JSFunctionSpec:
the extra field is documented as:
extra	uint16	Reserved for future use.

but it is:
/* number of arg slots for local GC roots */
(jsapi.h and some tutorial afair)

.