Basically, me and my colleagues (not native English speakers) had a discussion on whether we need "the" or not in this sentence:
Administrative / system passwords shouldn't be used in the code.
I've read this and this, but these posts do not talk about "the" usage with the word. I've also inspected this MS article for occurrences of "code", but they do not necessarily talk about code in general sense.
In the sentence in question the word "code" is used as a programming jargon, so it's uncountable. We talk about coding practice in general (that applies to both, already written code and future coding). So that's a general type of recommendation.
The situation is that we found some code having this issue. So, this is the reason why we write the recommendation. But we never mention or by other means point to the exact code, we just know it is there. We want to make the recommendation sound like it is also for future coding.
As long as it might have some tint of "locality", as Useless states, this is a reasonable candidate for a universal rule! On this page it can be seen that in some cases the can be used while talking about the general case:
We also use the definite article:
• to say something about all the things referred to by a noun:
The wolf is not really a dangerous animal. (= Wolves are not really dangerous animals)
The heart pumps blood around the body. (= Hearts pump blood around bodies)
We use the definite article in this way to talk about musical instruments:
Joe plays the piano really well. (= Joe can play any piano)
She is learning the guitar. (= She is learning to play any guitar)
• to refer to a system or service:
How long does it take on the train.
I heard it on the radio.
This is EXACTLY why the question arose at the beginning, as we all agreed that this is a general recommendation for all the cases in the universe.
(Your answers did not touch on this type of "the" usage so far. If you did, this might solve the dilemma. Could it be the case that the examples I've just pasted are only applicable to countable things, therefore, would not apply to "code"?)