Open-Ended Activities (and “make Them Critical”)

An open-ended activity (or open-ended chain) is work that does not tie into the project finish — usually a missing successor. Oracle does not print “no successor” on the pages below; it says “open-ended activities” and “open-ended chain.” Treat “no successor to the finish” as the planner read, not an Oracle sentence.

What the field is

Those activities can show critical (low/zero float) without being on the path that sets the project end date. Oracle (Shortening the critical path): “Activities can appear critical without being on the critical path, if they are part of an open-ended chain.”

Professional / EPPM schedule option: Make open-ended activities critical. “Determines whether to label open-ended activities as critical during scheduling.” Default in the UI is a checkbox you can clear. Oracle’s own advice when you want the driving path: Tools > Schedule > Options > General — clear that checkbox so open-ended chains drop out of the critical filter.

XER: SCHEDOPTIONS.sched_open_critical_flag. Stored Y/N is unverified. Do not invent it.

What it is not

It is not Longest Path, and it is not a missing predecessor (that is a dangling start). Define critical activities as Total Float ≤ n versus Longest Path is a different pair of options. Longest path: activities whose early finish equals the project’s latest early finish, then driving relationships back to start. Open-ended chains can still pollute a TF≤0 critical list.

Calculate float based on end date of Each project versus Opened projects also changes float on open-ended activities when several projects are open — more float under Opened projects. Multiple float paths is the more accurate “which chain actually drives” tool. Oracle: TF or longest-path flags can still mark activities that do not affect the project end (open-ended or constraints).

Microsoft Project has no “make open-ended critical” checkbox. A task with no successor gets float to the project finish (or status/constraint). Do not assume a P6 critical bar is a Project critical bar after conversion if this option was on.