Learn · Scheduling 101
Pinned dates: bounding when work may start or finish, and what it costs
After this subject you can set a bound on purpose rather than by habit, say what it costs the rest of the schedule, and read what Brikt does when the work cannot reach one.
Some dates are not the schedule's to work out
A permit lands on a date somebody else controls. A piece of equipment that takes four months to build arrives when it arrives. A contract names a milestone and attaches money to it. None of those comes out of the work — they arrive from outside it, and the schedule has to be told about them.
Telling it a bound
A constraint is a bound you put on when a piece of work may start or finish. Brikt gives you four: start no earlier than, must start on, finish no later than, must finish on. A no-earlier-than bound is a floor under one edge. A no-later-than bound is a ceiling over it. The two must-bounds are both at once.
The plain word for it
A pinned date is a date somebody set by hand rather than one the logic worked out. Brikt's help card says a pinned date holds an activity to the calendar, and the grid's start column reads computed from predecessors unless a constraint is set. That is the common case: a floor only binds when it sits LATER than the work would have given you.
What each one takes away
A floor that binds takes the date away from the arithmetic. A no-later-than ceiling that binds takes something else: it never moves the dates the forward pass worked out, it lowers how late the piece may run. A bound that binds neither way changes none of those dates and none of the room today.
Why it matters — two bounds that look alike in the date cell can do completely different things, or nothing at all.
When the bound and the work disagree
Set a ceiling the work in front of it cannot reach and the two do not agree. Brikt does not quietly move the date to make the picture fit, and it never pulls work earlier than the logic allows to meet a bound. It works the schedule out anyway and shows you the clash. What that looks like on the row is the next lesson.
Before you set one
Ask
Where is this date coming from — the work, or somebody outside it?
Instead of
Just put the date in.
Ask
Is this a floor or a ceiling, and which edge is it on?
Instead of
It is locked to the twelfth.
Ask
If the work in front of it slips, what do we want this date to do?
Instead of
We will deal with that when it happens.
What to remember
- A constraint is a bound you put on when a piece of work may start or finish.
- Brikt sets four: start no earlier than, must start on, finish no later than, must finish on.
- A pinned date is one somebody set by hand rather than one the logic worked out.
- A floor that binds pushes the computed date later; a no-later-than ceiling that binds never moves that date, and takes room away instead.
- When the work cannot reach a ceiling, Brikt shows the disagreement rather than hiding it.
Count the ones you already have
Open a project and look down the start and finish columns for the dates somebody set by hand. For each one, say out loud where the date came from and what you would want to happen if the work in front of it ran late. If most of them have no answer, that is the finding. Bring a schedule to a demo and we will go through it together.