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I have found an example for clearing all symbol definition by:

ClearAll["Global`*"]

But what does the symbol ` mean? It isn't the apostrophe ', yet it is not documented in Mathematica help.

Jim

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    $\begingroup$ It's a backtick. See this. $\endgroup$ Commented Jun 10, 2013 at 17:27
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    $\begingroup$ It's related to the concept of Context in Mathematica, see this. $\endgroup$
    – mmjang
    Commented Jun 10, 2013 at 17:28
  • $\begingroup$ @0x4A4D you are so fast! $\endgroup$
    – mmjang
    Commented Jun 10, 2013 at 17:30
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    $\begingroup$ You can learn a bit about the symbol ` in a different context than Context, see this: Meaning of backtick in floating-point literal $\endgroup$
    – Artes
    Commented Jun 10, 2013 at 17:36
  • $\begingroup$ Thanks, this is solved. How can I mark one of the comments as an answer? $\endgroup$
    – JimmyLin
    Commented Jun 10, 2013 at 18:54

1 Answer 1

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In Mathematica, the back-tick or grave accent ( ` ) is used for two purposes:

  1. As a context mark to delimit contexts (name spaces) in the full name of a variable.

  2. As a number mark to mark the end of an approximate number, and separate the number from its precision value.

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  • $\begingroup$ and what does that * symbol mean? I see in the documentation that it is used just in the Generalization & Extensions part. But I couldn't find the documentation about it? $\endgroup$ Commented Sep 20, 2015 at 21:10
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    $\begingroup$ I'm guessing your are asking about the * in ClearAll["Global`*"]. That * means zero-or-more-characters. It is documented here under Abbreviated String Patterns. BTW, posting your question as a comment to my answer is most inappropriate. It has nothing to do with my answer and nothing to do with the original question. In the future, please keep your posts on-topic. $\endgroup$
    – m_goldberg
    Commented Sep 21, 2015 at 4:15
  • $\begingroup$ ok, I thought it will be a duplicate if I post a new one! $\endgroup$ Commented Sep 21, 2015 at 4:41
  • $\begingroup$ @m_goldberg though to be fair, the question was about what ` means in the command ClearAll["Global`*"], and your answer mentioned the meanings of ` in general but did not discuss its use in this context. $\endgroup$
    – WillG
    Commented Nov 14, 2019 at 18:56

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