It is in fact defined: http://dvcs.w3.org/hg/xhr/raw-file/8d4e9ccfdbd4/Overview.html#network-error
---

When something is said to be a network error run the request error steps for exception "NetworkError" and event error.

When something is said to be an abort error run the request error steps for exception "AbortError" and event abort.

When something is said to be an timeout error run the request error steps for exception "TimeoutError" and event timeout.

When something is said to be a request error for exception exception and event event run these steps:

[...]

9. Fire a progress event named event.

(In reply to comment #1)
> It is in fact defined:
> http://dvcs.w3.org/hg/xhr/raw-file/8d4e9ccfdbd4/Overview.html#network-error
> ---
> 
> When something is said to be a network error run the request error steps for
> exception "NetworkError" and event error.
> 
> When something is said to be an abort error run the request error steps for
> exception "AbortError" and event abort.
> 
> When something is said to be an timeout error run the request error steps for
> exception "TimeoutError" and event timeout.
> 
> When something is said to be a request error for exception exception and event
> event run these steps:
> 
> [...]
> 
> 9. Fire a progress event named event.

thanks for pointing that out; however, I see this does not use the formulaic language that is used in other event firing cases; namely, one of:

(1) fire an event named X
(2) fire a progress event named X

for consistency, I would suggest changing the text to use one of the above forms

It does use the "fire a progress event" algorithm; it's right there in step 9.

9. Fire a progress event named event.

where "event" is the parameter to the "request error" algorithm (eg. "error", "abort" or "timeout").

*** This bug has been marked as a duplicate of bug 16306 ***