2 questions about the nightly

Trel <[email protected]> Wed, 10 Sep 2008 18:31:09 -0400
Newsgroups gmane.comp.mozilla.multizilla
Organization The Mozdev Foundation - news server
Message-ID <[email protected]>
the blog says

# Install MultiZilla v1.8.3.5a or download the nightly (SeaMonkey v1.x only).
# Clear your XUL cache

Is it just the nightly that that is 1.x only or is both?
By clear XUL cache, does that mean disable xul cache, restart and enable again?