Is it possible to add an attribute to the Foreign Key type in the meta.xsd to indicate that a relationship is implied? While it is possible to introduce an FK relationship in the XML, there are situations in which you wouldn't want the program to assume that a PK is present. e.g. when using valid_from/valid_to dates on versions of a record. The FK may only be implied in the metadata but enforced programatically in the database code as it's impossible to do this using only constraints.
Knowing that the implied relationship is there without forcing a non-PK column to show up as a PK would be great. Having the relationship represented the same way as is currently done for the implied relationships, i.e. dotted line, would seem to be ideal.
What do you think?