Notifies Interchange that this tag must be checked for nesting. Only applies to tags that have HasEndTag defined, of course. NOTE: Your routine must handle the subtleties of nesting, so don't use this unless you are quite conversant with parsing routines. See the routines tag_loop_list and tag_if in lib/Vend/Interpolate.pm for an example of a nesting tag.
UserTag tagname CanNest