Hi Tania,
To answer your question about the custom field:
Insert a custom Text column (Text1 for example). Right click on the column
heading and select "Customize Fields" from the shortcut menu. In the
Customize Fields dialog box, select the Formula button and enter the
following formula:
IIf([Estimated]=1,"TBD"," ")
The formula will test to see if the duration is estimated and if so, display
the text "TBD" in the field. If the duration is not estimated (no ? next to
the duration measurement), it will be blank.
The bar will still show in the Gantt chart with the scheduled dates. If you
wished to, you could hide the bar by double clicking on the task to show the
Task Information button and on the general tab, click the "Hide task bar"
checkbox.
I hope this helps. Let us know how you get along.
Julie