Free Pascal allows all characters, digits and some special character symbols in a Pascal source file.
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Recognised symbols
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The following characters have a special meaning:
and the following character pairs too:
When used in a range specifier, the character pair (. is equivalent to the left square bracket [. Likewise, the character pair .) is equivalent to the right square bracket ]. When used for comment delimiters, the character pair (* is equivalent to the left brace { and the character pair *) is equivalent to the right brace }. These character pairs retain their normal meaning in string expressions.