An IPS may have three types of parent document:

• A superseded version that the present instance of the document wholly replaces (typeCode = RPLC). 
  
• A source document from which the present document is transformed (typeCode = XFRM). An IPS may be created by transformation from an already existing local Patient Summary or an IPS document. An example of this case is the creation of a derived instance in which translations are appended in order to facilitate the cross-border usage of this document; or the case in which a local patient summary is transformed to originate a new IPS instance.
  
• An original version that the present document integrates (typeCode = APND). Some cross-border legal agreements (e.g.  the European Digital Service Infrastructure for eHealth) require the patient summary to be accompanied by  a printable representation of the original national data / document this IPS comes from. The relationship between the IPS and this content may be tracked using this relationship. 

Note 1: even for countries not dealing with real documents in their National Infrastructures (e.g. data collected from local databases), this mechanism could be useful to identify the collection of data used for generating the epSOS CDAs, facilitating the information backtracking. In that case the ID might be that of the epSOS friendly document or of any other kind of intermediate document used for generating the NCP document input.
Note 2: even if none of the allowable relationships defined by the CDA standard (XFRM, RPLC, APND) fits perfectly with the described case; the APND relationship seems to be the one that fits the better. In fact “An addendum is a separate document that references the parent document, and may extend or alter the observations in the prior document. The parent document remains a current component of the patient record, and the addendum and its parent are both read by report recipients.”