* Typo.
* Add new UserTag parameter "Underride". This allows you to define
  a new UserTag for use, then later have that tag become part of
  the distribution Interchange without causing errors.

  Has the effect of ignoring the second definition of a tag
  if that tag begins its stanza with

  	UserTag  tagname  Underride

  Intended for allowing a new "strap" template admin and catalog
  template with a few new UserTag definitions distributed with
  the template, then have those tags be superseded by distribution
  Interchange tags. (The first of those is ts/tn/tv, for defining
  page titles, ephemeral JavaScript code, etc.)