c:file charset (and friends) for vnext ?

in (previous) previous weeks discussion, I brought up the need to
explicitly mark a file's charset listed from a zip's manifest (on c:file) …
to override any implicit 'dowsing' of charset.

     http://www.w3.org/XML/XProc/2013/03/20-minutes.html#item06

in terms of p:zip I decided to go the 'whole hog' and just replicate what
we do for c:data in its entirety eg.

<c:file
  content-type? = string
  charset? = string
  encoding? = string>
    string
</c:file>

the question remains;

do we want to consider this for vnext as well (all optional attributes) ?
Or just stick with charset attribute ?

regards, Jim Fuller