why is "content language" pragma processing not equivalent to HTTP Content-Language?

[travisleithead]

was:

I18N-ISSUE-129: document unclear on why content language pragma processing not equivalent to HTTP Content-Language?

Migrated from Bugzilla: https://www.w3.org/Bugs/Public/show_bug.cgi?id=22719
@aphillips

Pragma directives (http://w3c.github.io/html/document-metadata.html#pragma-directives)

The content language pragma processing is called out as "not equivalent to HTTP Content-Language", but it doesn't say how or why.

From the context, it appears that HTTP Content-Language doesn't affect document processing, so that would be the "how", but this should be spelled out.

The note is still there, and the reason is still ambiguous. Need to do a bit more research here, unless anyone's already figured it out.

[aphillips]

The actual text of the note is misleading. It says:

This pragma is almost, but not quite, entirely unlike the HTTP Content-Language header of the same name. [HTTP]

What it means is: this pragma is very different from the processing described in (any edition of) the HTTP RFC. This is observably a fact. The processing described here rejects a Content-Language pragma that contains a list of languages (what we call a "Language Priority List") which is allowed by HTTP.

Since this feature is non-conforming, spending time on improving the algorithm, though, seems like a waste of time. Instead, I'd suggest simply changing the note to read:

This pragma is not the same as the HTTP Content-Language header of the same name. HTTP Content-Language values with more than one language tag will be rejected as invalid by this pragma.

[chaals]

Agree with the proposed change, done in the PR.