I'd love to RTFM on this one...but in the "TeamSite Workflow Developer's Guide" Release 6.0, there are NO hits for "transferonly"

if you look in the iwwf.dtd, it very clearly exists as an attribute on an externaltask element...page 133 of said document explains associated attributes...all of them EXCEPT "transferonly"...
same for usertask, grouptask, updatetask, and cgitask...
no devnet hits other than when people have pasted in their .wft code and it happens to be included...
anyone have a clue??
thanks in advance,
-Rori