erd - Specialization of a Weak Entity in ER Diagram Modeling -

i've been making erd quite times but, encountered unique case follows*:

1. every account may registration
2. every registration requires acceptance period
3. every registration requires @ least 1 program or more
4. there 2 kinds of registration, uui registration , semas ui registration. registration can either uui registration or semas ui registration can't both (disjoint)
5. semas ui registrasion must either semas s1 registration, semas s2 registration or semas s3 registration (disjoint).
6. uui registration , semas s1 registration records registrant prior school
7. semas s2 registration , semas s3 registration records registrant prior university

from description know registration weak entity cannot exist without account, acceptance period , program. registration has specializations here.

so question is:

1. am allowed model uui registration , semas ui registration subclasses of registration weak entity?

2. if allowed, how model them? weak entities or strong entities?

thank of help!

*ignore attributes

while weak entity sets have existence dependency on parent entity sets, existence dependencies don't automatically mean entity set weak entity set. regular entity set can required participate totally in relationship, imposes existence dependency.

to identify weak entity sets, @ how they're identified. weak entity set's identity / primary key superset of parent's identity / primary key.

there's no restriction prevent weak entity sets having subtypes. however, haven't seen examples of how represent them on er diagrams. i'm inclined draw them in same way parent entity sets (i.e. weak entity sets) since have same identity. reason in classic er (before eer notation subtyping), way represent subtype weak entity set without weak key.