List Relation Paths

getRelaPaths returns the definition of RxNav's related-concepts graph. For example, an SCD's related PINs are found by following RxNorm's relationship from SCD to SCDC, then a second relationship, from SCDC to PIN. The two hops are represented as the "path" SCD, SCDC, PIN. The paths can be filtered by the starting or terminal term type. Scope: Active concepts in the current RxNorm data set that have an atom with SAB=RXNORM and SUPPRESS=N