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special character

Definitions:

  Any non-alphanumeric character that can be rendered on a standard, American-English keyboard. Use of a specific special character may be application dependent. The list of 7-bit ASCII special characters follows: ` ~! @ # $ % ^ & * ( ) _ + | } { “ : ? > < [ ] \ ; ’ , . / - =
Sources:
CNSSI 4009-2015

  A non-alphanumeric character that may be defined by one or more CPE specifications to have a special meaning when it appears unquoted in a WFN. Special characters typically trigger a processor to perform a given function. The rules for escaping CPE special characters are defined in the CPE Naming specification [CPE23-N:5.3.2].
Sources:
NISTIR 7696 under Special Character