Before marking, certified copy of that document can't be given. That's true.
Marking means, acceptance by the court to consider that document as evidence for the adjudication of the case in which that document was filed.
All the documents we submit may or may not be marked because some/any/all of them may miss the criteria required for court like 1. Is that Original or xerox copy, 2. If that is a stamped document, is that properly stamped or not and 3. whether that document really relevant to the case.... etc after duly considering the objections from the opponent party/counsel.