Fundamental understanding of P6 date fields

David, thanks for ref paper (hadn't come across  this paper only the Understanding P6 Dates one) - says everything and more. Do you thing P6 users understand any of this?

I first came across these problems in the late 90's when trying to match a subcontractor's stand alone P6 version with a company system one. They kept giving different dates even though we had agreed major default settings. We realised that to match systems you had to specify every setting that P6 had even if we were sure that the the setting had no effect on the F9 analysis.

Hello Peter,

1. ES: The Early Start date of an activity is the earliest point in time when the activity can logically begin based on its predecessors and any constraints.

2. LS: The Late Start date of an activity is the latest point in time by which an activity must start to avoid delaying the project finish date.

3. EF: The Early Finish date of an activity is the earliest point in time when the activity can logically be completed based on its ES and duration.

4. LF: The Late Finish date of an activity is the latest point in time by which an activity must finish to avoid delaying the project finish date.

5. PS: The Planned Start date of an activity is often user-defined and represents the initially planned or baseline start date for the activity.

6. PF: The Planned Finish date of an activity is user-defined and represents the initially planned or baseline finish date for the activity.

Critical Path: Activities that have zero float (difference between LF and EF, or LS and ES) are on the critical path. The critical path determines the minimum project duration and any delay in critical path activities will directly delay the project finish date.

These date fields (ES, LS, PS, EF, LF, PF) are fundamental in project scheduling software as they provide crucial information about activity timing, dependencies, flexibility, and criticality. Understanding how these fields are calculated and their significance helps schedulers in managing and controlling project schedules effectively.

Thanks,

sorry i was asking how P6 calciulates these fields not what they represent

for instance start activity 1  es date is a calculated field from the project start date which is an input field or data date if you have missed it.

activity 2 es date is activity 1 + duration of activty 1 which is an input field + any input logic (with chosen calendar) between them + activity 1 calendar + any internal and external contraints input + any resource / calendar levelling input data. P6 converts duration days or hours to unit minutes (or is it 0.6 mins?) and then does the calculation in minutes based on calendar working input hours (converted to minutes) per day and displays the result in the chosen format......... and so on.

Is that it or did I miss something?

Read Ron Winter's before replying.