Can PE ENC variables be used in hiera hierarchy definition?

[J.T. Conklin]

I'm one of the admins of a site running PE 2016.4.2. Over the last
year, we've migrated from our own puppet module organization to the
roles and profiles pattern.

Currently, we're setting the parameters for modules that are shared
by more than one role/profile on a per-node basis. This has a draw-
back that we have many node *.yaml files for roles with many hosts;
and we must remember to add addiitonal node *.yaml files whenever
new hosts are assigned to the role.

It would be convienent if we could have role-based *.yaml files. If
we create a 'role' variable in the PE ENC for each classification
group, can that be used in the hierarchy definition in hiera.yaml?
If so, what would happen for unclassified nodes where the new 'role'
variable is not defined?

Thanks,

--jtc