readonly Statement

The readonly statement freezes a variable. After a variable is marked as read only, a security policy file cannot change its value. In essence, the variable ceases to behave as a variable and becomes a constant.

The readonly statement has a global scope.

readonly { "variable1" [, "variable2", …] };
Do not allow changes to the following variables:
readonly { "CurrentUser", "CurrentCommand", "TargetHost" };