Each topic area should cover basic information as provided from the objectives in the BSDA Certification Requirements Document (2005). The book's mission statement is defined in the book's introduction.
The topics should answer: "what would I expect a junior admin to know about this objective and demonstrate usage of these commands?"
Each topic should cover basic syntax of common switches or uses.
Each topic should provide basic examples with input and output.
Each topic should provide a hands-on activity (lab) or practice exercises.
Each topic should be generic for all four main BSDs. If applicable and appropriate it can cover some specific OS for some specific areas. (The technical reviewers can help the authors with details for other BSDs.)
Note: if the entire topic is too specific to one BSD, then maybe it is not appropriate for the "BSDA Certification Requirements". This can be discussed as needed.