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I have a dilemma, I do not know how to shorten the expression, room temperature.
I used to write it as RT, but several times I've seen people abbreviate it as rt.

Which one is correct?

And what about ultraviolet? Why is it shortened to UV, but visible, shortened, is usually written as vis?

What are the rules for shortening words?

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Any initialism (be it "RT", "rt", "r.t."...) stands for "real-time" to me. :P – cHao Mar 19 '14 at 14:19

There are no strict rules. You can infer some rules from currently used abbreviations.

  • Room temperature consists of two words - abbreviation r.t. is appropriate
  • Ultraviolet is one compound word, UV is appropriate
  • Visible is one word, vis. is appropriate
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According to this source:

300 K is a generally accepted value for room temperature to simplify calculations. The abbreviations RT, rt, or r.t. are commonly used in chemical equations to denote the reaction can be run at room temperature.

Thieme Publishing uses r.t for their encyclopedias. This appears to be the generally accepted convention, but all 3 versions mentioned above are commonly used.

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