 In various languages, prefixes are used in identifiers, known as sigils.These are not unary operators – syntactically they are lexically part of the identifier, and have different semantics, such as indicating the data type of the identifier – but are syntactically similar to the dereference operator and can be confused with it.For example, in a shell script codice_40 is the dereference operator codice_39 applied to the variable codice_42, while in Perl codice_43 is a scalar variable called codice_44.