The Java EE 6 Tutorial, Volume I

IN Expressions

An IN expression determines whether or not a string belongs to a set of string literals, or whether a number belongs to a set of number values.

The path expression must have a string or numeric value. If the path expression has a NULL value, then the value of the IN expression is unknown.

In the following example, if the country is UK the expression is TRUE. If the country is Peru it is FALSE. IN (’UK’, ’US’, ’France’)

You may also use input parameters: IN (’UK’, ’US’, ’France’, :country)