A short form provider produces renderings of entities. These renderings are
strings which in general can be used for display and serialisation purposes.
A given entity only has one short form for a given short form provider.
However, a short form may map to multiple enntities for a given short form
provider. In other words, for a given short form provider the mapping from
entity to short form is functional, but is not inverse functional i.e. an
Matthew Horridge, The University Of Manchester, Bio-Health Informatics Group