Are there any standards for creating CRM systems?

Question

CRM

It is the standards for creating complex multi-level systems that are of interest, with a hierarchy of users, rights control, and other delights.

Answer 1

I have not met any standards, but we constantly analyze the architectures of CRM and ERP solutions of competitors.
The most frequently repeated patterns can probably be called standards.

Answer 2

no such standards

Answer 3

Well, I think it's worth starting from the standards and business rules for whom CRM. But it seems to me that everything results in solving the desires and problems of the client.
Moreover, there are limitations of the development environment.