Should I use an article before a combination of common noun and proper noun, like in the case of "mission Apollo" or "level X"?
Context: I am writing (casual academic prose) about the fact that the same name in different contexts may be used to refer to different things. Here is an example sentence (we are talking about "documents": documents are comprised of levels, each level has a name):
In principle, ? level X3 in one document has nothing to do with ? level X3 in another document.
Some possible options:
No articles at all
In principle, level X3 in one document has nothing to do with level X3 in another document.
"The" before each "level X3"
In principle, the level X3 in one document has nothing to do with the level X3 in another document.
"a" before each "level X3"
In principle, a level X3 in one document has nothing to do with a level X3 in another document.
no article for the first occurrence, then "the"
In principle, ∅ level X3 in one document has nothing to do with the level X3 in another document.
Which of these possible sentences are correct, acceptable or wrong? Are there other options?