MrC,
On the surface Mike's answer is correct, however there is generally
always a way to do something, maybe not exactly what you want, but often
close enough. First, what exactly do you mean by "assignment days"? Any
of the spare fields (e.g. Text1, Number1, etc.) can be displayed in or
around a Gantt bar. So, if there are only a small number of resources
(one is best) assigned to the task, whatever you are defining as
assignment days can probably be displayed on the Gantt. The value in the
spare field may be able to be defined using a formula or if that doesn't
work, VBA is always an option.
Hope this helps.
John