Perl Programming/Keywords/when

The when keyword
when is a flow-control keyword that is used in the for and given statements.

The form EXPRESSION when EXPRESSION is used in the for statement, the form <tt>when</tt> <tt>EXPRESSION</tt> in the <tt>given</tt> statement that is similar to the C <tt>switch</tt> statement.

Please consider that <tt>given</tt> is considered highly experimental!