What symbol is used to reference a profile variable within a query expression?

The symbol used to reference a profile variable within a query expression is the dollar sign ($). This convention is widely utilized in programming and query languages to denote that what follows is a variable. In this context, when referencing a profile variable, using the dollar sign makes it clear to the system that the following term should be interpreted as a variable rather than a literal string or constant value.

This convention helps to distinguish between static text and dynamic values, thereby allowing for more flexible and powerful query expressions. It aligns with practices seen in various coding languages where specific symbols denote variable references, enhancing the clarity and functionality of the code.