(My other post was closed as a duplicate, so I'm forced to copy it here.)

Are on/off-topic rules not clear enough?

The help page What topics can I ask about here? contains a vague list of subjects that are on- or off-topic. This list is the guide-line for us all, but it leaves many gray areas.

For example:

1. Electronic devices are off-topic, but then what else is a computer?
2. Phones are a de-facto electronic device that is off-topic, but tablets are on-topic, although the difference between them lessens continuously. In the very near future there won't be much of a difference between laptops and phones.
3. All Linux distributions are on-topic, except Android, but this isn't mentioned in the rules. If the reason is because there is an SE site for Android, then what about Ubuntu?
4. Programming questions are off-topic, but script programming is on-topic.
5. Material recommendations are off-topic and this has been extended to buying recommendations, but are all posts mentioning "buying" automatically off-topic?

Interpretations of these rules vary from one person to another. Not all posts that are flagged for closing are finally really closed. Some closed posts are reopened, some after only the most minor cosmetical edit (or none).

It seems to me that in many cases, the verdict of whether a post is off-topic comes down to a "gut feeling", rather than solid rules. I don't see this as bad, but maybe the rules need to be more precise.

Some puzzling examples I have encountered for posts that I answered and that were subsequently closed are listed below.

Gives TSX-NI an advantage for running virtual machines?

In the original version of the topic, the poster said that while searching for a computer to buy he encountered a hardware feature that he doesn't understand, and asks whether it has any bearing on his type of work. This was closed for material recommendation, although no materials were ever mentioned, just because buying was the motive. I easily reworded the post to comply, but was it really necessary?

How can one use CDMA(code division multiple access) in individual communications

The poster asks about how does CDMA work. This was closed because of the (unproven) claim that this technology is only used for networks of phone companies. Why would a technology that is used for communication between computers be off-topic?

I suspect that because of the prevalence of computer technology in modern life, with time the topic rules will become even harder to apply and even more arbitrary, and that even today there are too many unwritten rules.

As a side remark, there are some practical points which I miss in the rules:

• A question being too trivial is not a motive for closing,
• Ditto for no independent research attempted by the poster.

I think that the question of whether the (so-short) topics help page needs more precision or examples merits a discussion, or whether the current situation is seen as "good enough". However, I must admit that today, deciding whether a post is on-topic is a bit of a guess, and I'm really looking for some clarifications.

Note: I have added another answer with a try at making some rules more specific.