I’ve seen .: used two times now, and I really wonder what is? The first time I saw it was in an extract from the Swedish dictionary SAOL in NE. They used it something like this so:

History.: since year x

More lately I saw it used in this comment by @nodsocket@lemmy.world like so:

What make bikes so expensive?

R.: The willing of people to buy them.

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What is this? Were does it come from? Should I use it?

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Edit: thanks for all the answers :). It turns out it was actually used for abbreviation in the dictionary, they wrote “hist.” instead of “historia”.