June 8, 2023

External Late Finish Date Constraints


This is the third blog post in a four-part series about external early start date and external late finish date constraints. This post discusses external late finish date constraints.

External late finish dates are date constraints that the Primavera P6 software program adds during the import process of an *.XER data file into a Primavera P6 database. External late finish dates represent the latest finish date of lost successor relationships due to missing external schedule-to-schedule linkages. For example, when importing the EPC Project JKL work schedule below into a Primavera P6 database, the driving successor link from the EPC work activity B3020 to the Commissioning and Startup work activity R1020, “C/S Activity T,” is missing. Figure 1 shows EPC work activity B3020 without its driving successor link to the Commissioning and Startup work activity R1020.

Figure 1: EPC Activity B3020 Without Its Driving Successor Link to Commissioning and Startup Activity R1020

The Primavera P6 program attempts to simulate the missing successor logic link by assigning an external late finish date constraint date of 20 January 2023 to the forecasted finish date of EPC work activity B3020. If a work activity has an assigned external late finish date, then the work activity has a missing external successor relationship to a potentially unspecified work schedule. Similar to external early start dates, research is needed to determine the purpose of and reason for any unidentified external late finish date links.


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