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A metasymbol is a symbol used in a metalanguage to represent an arbitrary collation in the object language.

Metasymbols are deliberately taken from a set of symbols that are not in the alphabet of the object language in question.

On $\mathsf{Pr} \infty \mathsf{fWiki}$, metasymbols are usually taken from any of:

uppercase letters: $P, Q, R, \ldots$ and subscripted versions: $P_1, P_2, \ldots$
the Greek alphabet: $\phi, \chi, \psi, \ldots$ and their subscripted versions: $\phi_1, \phi_2, \ldots$
uppercase bold: $\mathbf A, \mathbf B, \mathbf C, \ldots$ and their subscripted versions: $\mathbf A_1, \mathbf A_2, \ldots$

Which system is in use on a particular page depends to a certain extent on the nature of the source work which has inspired it.

Also known as

A metasymbol can also be referred to as:

a metalogical variable
a metalogical symbol
a metasyntactic variable.

Some sources also use the term propositional variable, but this has subtly different meaning on $\mathsf{Pr} \infty \mathsf{fWiki}$.

Also see

  • Results about metasymbols can be found here.