There's a very old legacy tag that does this (or did). It's been a while since I ran the ACS, but it's still in ad-html.tcl on ACS 3.x.
# this must stand for "do not disturb"
# if you put it into a static .html file, the
# following Tcl proc serves the page unmolested
proc ad_dnd_tag {} {
return "<!--AD_DND-->"
}
I usually stick this right after the opening <HTML> tag.
