I think what you missing is what the PRM and the CDT program are about and who they are for.
From the PRM on its benefits (Page xxviii):
…the PRM is designed to be an accessible resource for all project participants, including owners, architects, engineers, design-builders, contractors, construction managers, product representatives, financial institutions, attorneys, regulatory authorities, and facility
managers. In this respect, it serves and reflects the need for mutually dependent processes of design, construction, and facility use."
CDT Description from CSI Website:
"The Construction Documents Technology (CDT) Program provides a comprehensive overview for anyone who writes, interprets, enforces, or manages construction documents. Project architects, contractors, contract administrators, material suppliers, and manufacturers representatives are all realizing the advantages of being Construction Documents Technologists.
By being able to understand and interpret written construction documents, CDTs perform their jobs more effectively. By understanding the roles and relationships of all partipants, CDTs improve communication among all members of the construction team.
CDT Exam Overview
CDT candidates must demonstrate their knowledge of CSI’s recommended practices in the following subject areas:
The construction process
- Construction contract types
- Modifications and substitution procedures
Contractual relationships
- Rights, duties, and responsibilities
- Contract provisions
- Relationship and organization of construction documents
Use of construction documents
- Organizational formats
- Interpreting construction documents"
The PRM and the CDT program is for all the participants, about the total process, and includes the relationships among all the participants including the relationship between contractor and manufacturer.