CODEWITHSUNDEEP
internet-explorerhttp-headersmeta-tagsmicrosoft-edgeweb-standards
FlightPlan
FlightPlan

Reputation: 732

In the X-UA-Compatible tag, what do the "X" and "UA" actually stand for?

I'm curious about the meaning of the letters, and haven't been able to find an answer. What are they abbreviations for? I already understand how the tag is used. (There's an excellent summary of usage and history here).

Upvotes: 0

Views: 695

Answers (1)

BoltClock
BoltClock

Reputation: 723538

The "X" is a prefix conventionally used by vendors to denote non-standard HTTP headers. It has since been deprecated.

"UA" stands for user agent. For most users, the user agent is the web browser, so it makes sense in context.

I'm surprised none of the documentation for X-UA-Compatible actually says what "UA" stands for. Perhaps the documentation simply assumes the author already knows. It doesn't help that web searches for "UA" turn up entirely different expansions for the same abbreviation altogether.

Upvotes: 4

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