Task Calendars?
 

I'm trying to schedule a construction project where several tasks are restricted so that they can not be done during winter months. The project runs over three years, so there are three winter seasons; three blocks of time not available to do these tasks. How can I set this up in OmniPlan to constrain those tasks to be done in summer months only?

All of my resources can continue to work in the winter, but just not on these particular tasks.

I guess what I've looking for is something akin to "task calendar" in MS Project. Can I do that in OmniPlan?