Re: Use of "level" or "version" parameter to denote use of experimental features?

Neil Katin (
Tue, 17 Jan 95 00:49:19 EST

> From: Larry Masinter <>
> I've been wondering if we might allow some way to designate with the
> "level" or "version" parameter (or some other parameter) for
> describing a document that is mainly 'text/html' but also contains
> experimental features. E.g.,
> text/html; level=x-w3org-3
> This would allow folks to experiment with minor increments for which
> saying "text/html; level=3" would be wrong.
> Do you like the idea? If so, should it be "level", "version", or some
> other parameter?

A word of warning from someone who worked in MIME: unless you
clearly define what the semantics of "level" is, it will be
nothing but a comment for human readers.

MIME has a "Mime-Version: 1.0" field in it. We never defined
what should happen if the field value wasn't "1.0". Some readers
ignored the value; some insisted it be exactly 1.0 or they would
reject the message. The end result was the field was useless.

So be clear what the semantics of the field are. Does it pre-suppose
backwards compatability with prior versions? What are the naming rules?
What should a reader do with an unrecognized version? Or is the field
for debugging only, and the reader should take no action based on the
field value.

Anyway, that's my 2 cents...

Neil Katin