@specified_duration(string)
@specified_duration(exe)
@specified_duration(proc)

returns in the specified duration of the argument. The argument must refer to an action (through its label), an exe or the name of a proc. The specified duration is:

The specified duration can be computed only if the delays of the involved actions are given statically (as constant). If this is not the case (some delays are specified by an expression that is evaluated at the right moment, then @specified_duration returns -1.