Can I use comma as separator or something else?
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There’s no way to do this right now.
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I’ve thought about this too - also searching for tags within categories. Some sort of advanced search form offering various filters would help… probably already discussed elsewhere but this is the first time I’ve thought of it.
Ah. here it is.
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Ok, good to know 
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Is this still true now @neil
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We now have a way to search for multiple tags in advanced search:
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