Relates an Act to its subject Act that the first Act is primarily concerned with.
\nExamples
\nConstraints
\nAn Act may have multiple subject acts.
\nRationale
\nThe ActRelationshipType "has subject" is similar to the ParticipationType "subject", Acts that primarily operate on physical subjects use the Participation, those Acts that primarily operate on other Acts (other information) use the ActRelationship.
\nhttp://terminology.hl7.org/CodeSystem/v3-ActRelationshipType
where concept is-a SUBJ