What is the meaning of #XXX in code comments?

Question

I have seen this a lot in code, even vim marks it as a special case. #TODO and #FIXME are two other fix markers vim highlights but what does

Answer 1

Some notes from a June 2005 Python Enhancement Proposal that was rejected.

Choosing between FIXME and XXX is difficult.
XXX seems to be more common, but much less descriptive.
Furthermore, XXX is a useful placeholder in a piece of code
having a value that is unknown.

Thus FIXME is the preferred spelling.
Sun says that XXX and FIXME are slightly different, giving XXX higher severity.
However, with decades of chaos on this topic, and too many millions of
developers who won't be influenced by Sun, it is easy to rightly call them synonyms.

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The PEP Starts with,

This PEP has been rejected. While the community may be interested,
there is no desire to make the standard library conform to this standard.

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What Are Codetags?

Programmers widely use ad-hoc code comment markup conventions to serve as reminders of sections of code that need closer inspection or review. Examples of markup include FIXME, TODO, XXX, BUG, but there many more in wide use in existing software. Such markup will henceforth be referred to as codetags. These codetags may show up in application code, unit tests, scripts, general documentation, or wherever suitable.

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The PEP is an interesting read.