Article before common noun + proper noun (e.g., "mission Foo")?

Question

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:

1. No articles at all

   In principle, level X3 in one document has nothing to do with level X3 in another document.

2. "The" before each "level X3"

   In principle, the level X3 in one document has nothing to do with the level X3 in another document.

3. "a" before each "level X3"

   In principle, a level X3 in one document has nothing to do with a level X3 in another document.

4. 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?

Answer 1

Article are one of the most troublesome topics here as I can see. In general the rule I stick to is this:

Use "the" when you speaking about some specific thing or things, or things that are unique, or when speaking about something in general (sometimes "the" can already be part of the thing):

• The history books from the library on 11 Wales st. are no different from the history books from the library on 67 Brooklyn st. (Specific books from specific places)
• The tigers from Ranthambore are no different from the tigers from Kaziranga. (Any tiger from one specific place and any tiger from the other specific place)
• The Earth in our reality is much older than the Earth in the game about dinosaurs. (A unique thing - the planet Earth)
• The Dark Side of the Moon by Dream Theater is as good as The Dark Side of the Moon by Pink Floyd. (The same album - The Dark Side of the Moon played by different bands)

Use "a/an" when speaking about any thing in general.

• A bird that has long wings flaps them less often than a bird that has short wings. (Any bird with long wings (unspecific) and any bird with short wings (unspecific))

Use "no article" when speaking about some things in general or uncountables in general.

• Water from the tap is different from water in bottles. (Uncountable water from the ta[ (in general) and uncountable water that comes in bottles (in general))
• Cars made in Germany are better than cars made in America. (Any car that is made in Germany (in general) and any car that is made in America (in general))

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As for Proper Nouns, they come with different rules for using "the".

In your example however either "the" or "no article" is best since you're referencing a unique (specific) thing. An example:

• In general, (the) Deckard Cain in Diablo 1 and 2 looks very different from (the) Deckard Cain in Diablo 3.

However, if you were to speak about something in general you could either use "the" + plural, "no article" + plural, or "a/an" + singular:

• In general, the weapons/weapons/a weapon in Counter-Strike 1.6 dealt more damage than the weapons/weapons/a weapon in Counter-strike: Source.