A relationship that is established based on knowledge of best practices within a particular application area or an aspect of the project where a specific sequence is desired. Based on project management in terms of time, discretionary dependency is sometimes referred to as preferred logic, preferential logic or soft logic.
It is established based on knowledge of best practices within a particular application area or some unusual aspect of the project where a specific sequence is desired, even though there may be other acceptable sequences. Discretionary dependencies should be fully documented since they can create arbitrary total float values and can limit later scheduling options.
When fast tracking techniques are employed, these discretionary dependencies should be reviewed and considered for modification or removal. The project management team determines which dependencies are discretionary during the process of sequencing the activities.
This term is defined in the 5th edition of the PMBOK.