Expressions return a value of a specific type. Expressions used to display data must return a character value. Expressions used to enter or edit data must return the same type as the field. Expressions used to query data or for conditional display must return a logical value. Expressions used to sort data in an index expression may be any type except logical.
Expressions consist of constants, operators, field values, and functions.
The most common form of expression is the name of a field. In this case, the type of the expression is the type of the field. Field names, constants, and functions may all be combined to form expressions. Recent versions of FoxPro and dBase have added many new expression functions which are not supported by baserunner. An expression used within a tag in a template will be be replaced by the character value returned by the expression.