Update App_Use_Cases.tex

Co-authored-by: Stephen Herbein <[email protected]>
Signed-off-by: Swaroop Pophale <[email protected]>

App_Use_Cases.tex

@@ -481,7 +481,7 @@ \subsection{Use Case Details}
 
 PMIx PSETs are used for query functions (\code{MPI_SESSION_GET_NUM_PSETS}, \code{MPI_SESSION_GET_NTH_PSET)} and to create \code{MPI_GROUP} from a process set name.
 
-PMIx groups are used during creation of \code{MPI_COMM} from an \code{MPI_GROUP}. The PMIx group constructor returns a 64-bit PMIx Group Context Identifier (PGCID) that is guaranteed to be unique for the duration of an allocation (in the case of a batch managed environment). This PGCID could be used as a direct replacement for the existing unique identifiers for communicators in MPI (E.g. Communicator Identifiers (CIDs) in Open MPI), but may have performance implications.
+In OpenMPI's MPI Sessions prototype, PMIx groups are used during creation of \code{MPI_COMM} from an \code{MPI_GROUP}. The PMIx group constructor returns a 64-bit PMIx Group Context Identifier (PGCID) that is guaranteed to be unique for the duration of an allocation (in the case of a batch managed environment). This PGCID could be used as a direct replacement for the existing unique identifiers for communicators in MPI (E.g. Communicator Identifiers (CIDs) in Open MPI), but may have performance implications.
 
 There is an important distinction between process sets and process groups. The process set identifiers are set by the host environment and currently there are no PMIx APIs provided by which an application can change a process set membership. In contrast, PMIx process groups can only be defined dynamically by the application.