(See http://build.fhir.org/codesystem-concept-map-relationship.html)

The concept map relationship codes for both the broader and narrower relationships between source and target concepts are inherently directional.  If the single words "broader" or "narrower" are used for these code, then they are subject to misinterpretation when presented in different contexts.  For example, in a table with columns "source" "relationship" "target", or in the ConceptMap resource where the "relationship" element hangs off the "target" element.

Thus the codes for these concepts MUST explicitly state the directionality to avoid ambiguity.

These codes should thus be replaced with:

source_has_broader_target "The source is included in target"

source_has_narrower_target "The target is included in the source"