Must Start on

Hi Planners,

A baseline schedule showing that the start date of the project "milestone task" is not critical "9 days float", some of the succesor tasks has a constraint "start no earlier than". I changed the constraint of those successors to "Must start on" and I got the start date critical. Is there any explanation to this?

Regards,

Microsoft Project
T
Tom Boyle 👤 Member for 19 years 6 months
· Permalink

Moutaz,

Look closely at the early and late dates of your affected tasks.

  1. According to your description (and ignoring other impacts), at least one of your successor tasks already has a logic-driven early start date that is 9 days later than its SNET date. 
  2. SNET constraints on the successor tasks only have the potential to affect their early dates - with no effect on your project start milestone.
  3. By changing the SNET constraints to MSO, you are completely over-writing both the early dates and the late dates on those tasks.  The backward pass carries this effect back to the late dates of your project start milestone.

MSO/MFO constraints in MSP are similar to Mandatory constraints in P6.  I avoid them in general.  If Total Slack or the "Critical" flag is to be relied on, then you must never assign them to any logically-connected task.  I wrote more about this last year: http://wp.me/p6CCB4-7w

Forum Sponsor

Top Posters

Julian Pegg
1 posts
Peter Nagy
2 posts
Raymund de Laza
17 posts
Syed_Asad
0 posts
Tony Greyvenstein
0 posts
Ahmed Al-Jubouri
13 posts
Umar Alvi
3 posts
Sibusiso Mahlalela
0 posts
Michael Samanyayi
3 posts
Simon Gumede
0 posts