EU legislation envisions that individual should have access to some information about the logic of the processing of their personal data. This right is distinct to the right of access itself.
For instance, the consolidated Irish Data Protection Act 1988 includes the following provision (Art. 4.1.a.(iv)):
The Dutch data protection law would be broader, and would not include the restriction on "significant effects".
In addition, each Member State law envisions exceptions to this right of access to the "logic of the processing", often different from exceptions to the right of access itself. Usually, but not always, these exceptions would include practical feasibility, cost, trade secrets and intellectual property considerations. A good reference on the topic is Trade Secrets v. Personal Data: a possible solution for balancing rights.