When derivatively classifying information, where can you find a listing of specific information elements that identify their classification, reason for classification, downgrading, and declassification information?

Security Classification Guide

Explanation:

"Derivative classification" is defined as incorporating, restating, paraphrasing or generating in a new form of information which is already classified, as well as marking those newly developed material consistently with classification markings that apply to the source information.

The original classification decisions is kept as a record as a security classification guide which can be used as source document at times when derivatively classified documents are created.

Hence the answer is - - Security Classification Guide