LOCATABLE and LINK are common-types, used also by PARTY (demographic package), yet the specification is assuming (explicitly) that it will target EHR content.
see 'target' attribute type on https://www.openehr.org/releases/RM/latest/docs/common/common.html#_link_class
or LINK class description.
To fix this we will have to relax 'target' format by chnaging type to DV_URI instead of DV_EHR_URI.
This related to in the sense that it is a similar concept/principle.