What is the difference between conjunctive present and perfect with ne?

Question

I have seen both present and perfect forms of the conjunctive for negative orders or requests, for example ne canas and ne cecineris. What is the difference? Is one more an order and the other more a request? Are they interchangeable?

I am interested in these as orders, either as separate exclamations or as part of a governing clause, not subordinate to anything else. The standard I have learned for negative imperative is either noli(te) with infinitive or ne with perfect conjunctive. I have the impression that ne with present conjunctive is more of a request, but I am unsure.

There is a similar earlier comparison for hesitation, but it does not cover orders or requests.

Answer 1

If you intend to use it as an order similar to noli(te), the conjunctive perfect is probably the best way to go. To the best of my knowledge, there is no difference between the present and the perfect version as the time is just a formal one rather than an actually a content-related one in this case. Moreover, the time does not have any influence on whether the sentence is meant as a request or as an order since a request would start with utinam and then a perfect would indicate that the chance of performing the request is already over. Nonetheless, the perfect is more common in your use case and - as you've said yourself - what is teached in schools. In fact, I have never seen a ne+Konj.Präs. other than the negative form of the conjunction ut whatsoever. Therefore, it should be more safe to choose the perfect.