The two types of delays are before and after delays. They specify an amount of time relative to the completion of the previous step (or to when the pre-condition became true in case of the first step).
For a before delay, the step must be initiated before that delay. For an after delay, the delay needs to pass before the step can be executed. None, only one or both delays may be included in an operation instance statement.
A before delay syntax is
An after delay syntax is
A duration_specification specifies a time amount as follow
A value is a word that may refer to a number or not.
A unit must be one of: "mmsec", "microsecond", "msec", "millisecond", "sec", "second", "min", "minute", "h", "hour", or "day".