Available inall subroutines.
Declares a local variable.
declare local var.expiry_time TIME;
User-defined variables must be declared
local, prefixed with
var., and must be declared with a type. They are scoped to the subroutine, and must be declared before they are first used.
Since variables have subroutine scope, it usually makes sense to define them at the top of a subroutine.