According to the PMBOK® Guide, specifically within the Sequence Activities process, there are four types of logical relationships or dependencies used in the Precedence Diagramming Method (PDM). The acronym FF is the standard shorthand for a Finish-to-Finish relationship.
In project scheduling, a Finish-to-Finish relationship is a logical relationship in which a successor activity cannot finish until a predecessor activity has finished.
Example: Writing a document (predecessor) must finish before the editing of that document (successor) can finish. The editor can start while the writer is still working, but they cannot complete the final edit until the final draft is received.
Visual Representation: In a network diagram, the arrow goes from the finish of the predecessor to the finish of the successor.
A. Fixed Fee: This is a term used in Procurement Management (specifically Fixed-Price contracts like FFP or FPIF), referring to the payment structure, not activity sequencing.
B. Free Float: While " FF " is sometimes used informally by practitioners to mean Free Float (the amount of time an activity can be delayed without delaying the early start of its successor), in the specific context of sequencing activities and PDM relationships, it strictly stands for Finish-to-Finish.
C. Fixed Finish: This is not a standard PMI term. The standard term for a set date is a " Finish No Later Than " or " Finish No Earlier Than " constraint.
To provide a complete picture of sequencing, the four standard acronyms are:
FS (Finish-to-Start): The predecessor must finish before the successor can start (Most common).
SS (Start-to-Start): The predecessor must start before the successor can start.
FF (Finish-to-Finish): The predecessor must finish before the successor can finish.
SF (Start-to-Finish): The predecessor must start before the successor can finish (Rarely used).
