Understanding date constraints

Q & A
#1

I just created two events, A and B, and had set B to the dates 1142-1146, and then edits A and sets the dates to 1142-1142 (i.e. zero duration). I add a constraint on A that it “End equals start of” B with an offset of zero. I then add a duration of A of 16 years – and B is moved 1158-1165.

What is the logic on which event is moved and which if start and end times are changed when the duration is changed?

Does Aeon always look forward in time and fixes the start date of the first event in a dependancy chain and then calculate all dates from that, or is is possible to fix the end date of event A so any changes of the duration changes the start date?

#2

That is an interesting question. It It got me experimenting a bit with Aeon Timeline 2. It is actually possible to define multiple events with conflicting dependencies, so that in the end an event is shifted in such a way that its dependency is no longer satisfied. There is no warning or anything.

Update
It seems like AT2 doesn’t look forward in time. If you create a dependency between two events, the subsequent one may be adjusted. If there are multiple and conflicting dependencies, the predecessor with the later end prevails.

#3

I was hoping for an official answer rather than doing some reverse engineering, but we’ll see how much I use this function. If I use it much, I’ll simply need to experiment. I’m quite used to MS Project and it also has its antics.

#4

Currently when resolving constraints, only item dates will move, not duration.

This was initially set up to be useful to project management in particular (where duration is the more known value), however we are aware that other use cases would prefer the duration to change instead. Therefore it is on our list to possibly look at in the future.

#5

I see, I was more interested in the logic for the start and end dates when the duration changes.

In my example, when I change duration of an event (A in this example), will always the start time be fixed and the end time change, or are there circumstances where the end time is fixed and the start time will change?

#6

No, when you change the duration of the event it will always change the end date.
If changing the duration violates a constraint, then it will move an event rather than adjust its duration (eg. keeping the end date fixed and moving the start date).

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