A parallel program archetype aids in the development of reliable,
efficient parallel applications with common computation/communication
structures by providing stepwise refinement methods and code libraries
specific to the structure.  The methods and libraries help in 
transforming a sequential program into a parallel program via a
sequence of refinement steps that help maintain correctness while
refining the program to obtain the appropriate level of granularity
for a target machine.  The specific archetype discussed here deals
with the integration of task and data parallelism by using collective
(or group) communication.  This archetype has been used to develop
several applications.