L.4.15.3.1.4 Relationship

A relationship is a connection between any two model elements. An example of where a relationship would be used can be seen in figures 1 and 2. In each of those examples, the arrows between the nodes have relationships defined. A relationship is defined as follows:

<xsd:complexType name="CT_Cxn">
  <xsd:attribute name="modelId" type="ST_ModelId" use="required" />
  <xsd:attribute name="type" type="ST_CxnType" use="optional"
    default="parOf" />
  <xsd:attribute name="srcId" type="ST_ModelId" use="required" />
  <xsd:attribute name="destId" type="ST_ModelId" use="required" />
  <xsd:attribute name="srcOrd" type="xsd:unsignedInt" use="required" />
  <xsd:attribute name="destOrd" type="xsd:unsignedInt" use="required" />
  <xsd:attribute name="parTransId" type="ST_ModelId" use="optional"
    default="0" />
  <xsd:attribute name="sibTransId" type="ST_ModelId" use="optional"
    default="0" />
  <xsd:attribute name="presId" type="xsd:string" use="optional"
    default="" />
</xsd:complexType>

The relationship, as with the element, has a unique id associated with it referred to as the modelID. The srcId and destId attributes refer to ids of the source element and destination element, respectively, that this relationship is defined between.

The srcOrd and destOrd refer to the ordinality of siblings for a given connection. For example, if a node had three siblings, A, B, and C, then the srcOrd would define if they were to show up as A, B, C, or perhaps B, C, and then A.

The presId attribute contains the presentation that is associated with this particular relationship.