Documentation or clear definition to distinguish dates in Program Association from one another in base and sub classes

Summary of outcomes for Data Standard 3.3.0-a

• Problem Addressed: ParticipationStatus on GeneralStudentProgramAssociation should be a collection. Currently, it is not.
• High-level Reasoning: Changing ParticipationStatus to a collection allows for longitudinal tracking of multiple statuses for a single student. This was a part of the original model modification but missed when implementing. Ideally, allowing for multiple values to track Eligible versus Active versus Inactive, for example, should help clarify the confusion around the many program date elements.
• Changes to be Made: Create a new complex type ProgramParticipationStatus that will mirror the current ParticipationStatus but be an optional collection. The original ParticipationStatus will be deprecated.

Original Description:

There are several date fields in General Student Program Association and in the individual sub classes. The handbook provides definition for the dates. It is still not clear for the community on when to use these dates. . Is there a way to document this clearly as part of the UDM Model or Handbook or a separate documentation? Some of the ambiguity that I found are below:

I am clear on GPA.BeginDate which is when the student has become eligible to participate or receive services. I am not that clear on the participation.statusbegindate vs IEPBeginDate vs ServiceBeginDate.

GeneralStudentProgramAssociation.Begin Date = Student eligible to participate in a program and can start receiving services
GeneralStudentProgramAssociation.ProgramParticipation.StatusBeginDate = The date student starting to participate in a program. How is this different from the IEPBeginDate if there is only one IEP service that the student receives
StudentSpecialEducationProgramAssociation.IEPBeginDate = Handbook says effective date of the most recent IEP. If a student is participating in only one IEP program and starts receiving services then it will be the same as the service begin date too, right? – What is the reason behind capturing the most recent IEP date while agencies can see this from the last Service.ServiceBeginDate?