5.6. InsertHTML

This attribute makes HTML tag output be inserted into the containing tag, in effect adding an attribute=value pair (or pairs).

    UserTag tagname InsertHTML   htmltag  mvtag|mvtag2|mvtagN

In Interchange's standard tags, among others, the <OPTION ...> tag has the [selected ..] and [checked ...] tags included with them, so that you can do:

   <INPUT TYPE=checkbox
        MV="checked mvshipmode upsg" NAME=mv_shipmode> UPS Ground shipping

to expand to this:

   <INPUT TYPE=checkbox CHECKED NAME=mv_shipmode> UPS Ground shipping

Providing, of course, that mv_shipmode is equal to upsg. If you want to turn off this behavior on a per-tag basis, add the attribute mv.noinsert=1 to the tag on your page.