Merge branch 'v4' into sync-m-to-v4

Chap_API_Struct.tex

@@ -171,6 +171,9 @@ \subsection{PMIx Return Status Constants}
 \declareconstitem{PMIX_ERR_BAD_PARAM}
 One or more incorrect parameters (e.g., passing an attribute with a value of the wrong type), or multiple parameters containing conflicting directives (e.g., multiple instances of the same attribute with different values, or different attributes specifying conflicting behaviors), were passed to a \ac{PMIx} \ac{API}.
 %
+\declareconstitemNEW{PMIX_ERR_EMPTY}
+An array or list was given that has no members in it - i.e., the object is empty.
+%
 \declareconstitem{PMIX_ERR_RESOURCE_BUSY}
 Resource busy - typically seen when an attempt to establish a connection
 to another process (e.g., a \ac{PMIx} server) cannot be made due to a