Tokens of all kinds may be included in expressions.
Expressions used in Conditions do not require the leading "=" sign which is typically used before formulae in other types of attributes. Values are generally compared using a comparison operator and, when expressions use string or ambiguous data types, both sides of the equation should be enclosed in double-quotes. More complex expressions can be created using logical operators and parentheses.
Here are some example expressions:
Complete information about Built in Functions and Operators is available for your reference.
Generally, if the expression contains an error of some kind, such as a data type mismatch or a missing function argument, no error message is displayed in the browser; instead, the Condition just doesn't work as desired. However, an error message will usually be included in the Debugger Trace Page (see Debug Reports) at the point at which the expression is evaluated. So, if your Condition isn't working as you expected, check the Debugger page.