Mick,
I am not quite sure I understand what you mean by, "how do I determine
if a task is a deadline".
I have answered the second part of your question below.
If by deadline date you mean the "Deadline" field in Project then my
approach is as follows.
1. Create a numeric Custom field, say Number1.
2. Enter a formula to calculate the difference between the Finish date
and the Deadline date. For example, a simple version is:
DateDiff('d',[Finish],[Deadline]).
3. View the data as Numeric data to verify that the formula works as
desired.
4. Update the Custom Field to display Graphical Indicators instead of
Data in the "Values to Display" portion of the custom field dialog box.
5. Enter the conditions for each indicator and select an indicator. For
example, for my Red indicator if any task where the planned finish date
is more than 5 days later than the deadline then I would make my first
criteria, Less than -5.
Simply put, I create a numeric custom field with a formula and verify
the formula before I begin working with the indicators.
You could just as easily use a baseline field as the basis for
determining the lateness of a task instead of using the Deadline field,
assuming that you are saving the baseline.
Hope this helps,
Jim P.