Program announcements (PA)
Describes new, continuing, or expanded scientific priorities and program areas, follow the standard schedule for submission, review and award and are usually active for three years.
Program announcements with special receipt dates (PAR)
Provide their own submission schedules and are usually active for three years.
Request for Applications (RFA)
Describe an institute's or center's interest in receiving applications in specific area(s). These are usually one-time solicitations.