add commentary about groups being used for CDUs and redundancy groups for CDUs

Author: regrant

Common.tex

@@ -198,6 +198,12 @@ \section{Group Functions}\label{sec:Group}
 Groups can only contain objects from a single \texttt{PWR_cntxt}.
 Group operations that involve multiple groups must be performed with groups from the same context.
 
+Some groups may be created automatically by an implementation for the convenience of the user. Examples of such groups include
+a group of nodes assigned to a job or a group of objects being cooled by a CDU object. An implementation may choose to provide
+a group (or groups) of redundancy for CDU overlap where failures in a single CDU can be compensated for by other existing CDUs.
+Having such redundancy groups provides opportunities for users to determine if CDU failures can be compensated for by adjusting
+existing CDU capacity or if they require other actions to ameliorate. 
+
 %int PWR_GrpCreate( PWR_Cntxt context, PWR_Grp* group );
 \begin{prototype}{GrpCreate}
 	\longdescription{The \texttt{PWR_GrpCreate} function is used to create a new group which will be associated with and unique to the users context.}