The top result for most search engines on "sourceURL" is this article from 2009:
I don't believe there is an official specification. I think it would be reasonable for the SourceMap specification to take ownership, especially given the similarities with soruceMappingURL. It would probably be just a paragraph of text instead of a note.
On May 22, 2013, at 1:32 PM, Paul Irish wrote:
> Nope. it's only defined in the souce map spec.
> On Wed, May 22, 2013 at 12:40 PM, John Lenz wrote:
>> Is there any spec for sourceUrl outside the source map spec.
>> On May 22, 2013 9:52 AM, wrote:
>>> Excellent. Chrome would like to see sourceURL to be updated in the spec
>>> as well. Thanks all.
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