In re 'simple', ask Trevormonty who first included the acronym in his post (#9) but - I note - has since been answered by both Parksy and Gafferbill and - no doubt by your own 'Googling' prior to your post.
Was Mountain Bike. Only mentioned it because somebody recommended sealant they used on bike. Given totally different uses, I wouldn't recommend a MTB sealant for high speed high load vehicle tire without doing some more research.
The whole point here is that it would have been exceedingly helpful if, in the very first post, it was made clear, or even mentioned, that the enquiry was in respect of bike tyres rather than car or caravan.
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