@Root in the MEDITECH NPR Report Writer

You've initialized a standard MEDITECH NPR report, at once you recognize the infamous @Root macro.    What does it do?    The @Root macro is used to refer to a segment's top level segment also known as the root.    @Root(@edm.data.doc) translates to *(HE)HEAA[aa] which is the main segment.    Examine these MEDITECH data definitions for the segments below.

EDM.PAT.main[urn]
*(HE)HEAA[aa]

EDM.PAT.edm.data.doc[urn,doc.q]
*(HE)HEAA[aa]D[heDOC]