Alt text and media types for preformatted text

[Sean Conner]

It was thus said that the Great Nathan Galt once stated:
> 
> 
> On Mon, Mar 1, 2021, at 1:24 PM, Sean Conner wrote:
> > 
> >   While I would like to disallow control codes in the specification, that
> > might be too big of a change, and *will* affect some sites, but adding
> > verbiage that discourages it can be added.
>
> Perhaps this is the wrong way to frame this, but you're prioritizing
> backwards compatibility on a pre-1.0-spec to support an unintended hack
> that has security issues?

  If I recall, escape codes where *never* in any of the specifications, just
an oversight when documenting the format (aka "loophole").  

> If I had control codes on my capsule, I'd grumble a bit, sure, but I'd
> remove them. I'm not sure it's worth it to shield the tiny handful of
> **current** capsule operators from some search-and-delete work compared to
> all the future client implementors who'll face at least some pressure to
> implement color support (and, if they're actual terminal applications,
> open their users to keyboard-reset exploits).

  I'd ban control codes in a heartbeat (except for HTAB, CR and LF as
stated), but I'm not sure how popular that decision would be.

  -spc