current text "This identity is used by an assert and/or report element to specify that the expression specified in the expression attribute of the smlerr:output element must be evaluated to generate structured XML when the assert/report fires.    "

clarify existing content, and add relationship to smlerr:outputids, e.g. "This identity is specified on one or more assert and/or report elements' smlerr:outputids attribute.  Each time such an assert or report fires, the smlerr:output element's expression attribute is evaluated to generate structured XML.