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What symbols/characters are not allowed in tags?

I'm curious simply because I'm writing JS script that does tagging similar to SO, what characters are allowed in tags on SO?

Is it alphanumerics and some others like # and _?


1 Answer 1


From the side box that pops up when you are tagging a question:

How to Tag A tag is a keyword or label that categorizes your question with other, similar questions.

► favor existing popular tags; avoid creating new tags

► use common abbreviations

► don't include synonyms

► combine multiple words into single-words with dashes

► maximum of 5 tags, 25 chars per tag

tag characters: [a-z 0-9 + # - .]

► delimit tags by space, semicolon, or comma

so out of your set, _ is not permitted.

  • oh my. this's called selective dislexia.
    – Stann
    Aug 23, 2011 at 7:03

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