HTTP method names: upper or lower case?

Question

This may be a self answering question, but I'm hoping one of you could point me to any resource where it is declared, or can be inferred, whether to use upper or lower case letters when declaring a HTTP method name in HTTP or REST requests. The majority of examples I see put GET, PUT, POST, DELETE, PATCH etc in capital letters, whereas I go on the assumption that HTTP method field names are case insensitive - that is, for example, that "get" is equally as valid as "GET". Traditionally I have always used capital letters, but I would just like to be sure.

The W3C explicitly declares that the method is case-sensitive and uses upper case, but in my travails, I've often encountered HTTP method field values using lower case, which I assume are incorrect, so from my POV, it seems that practices and standards are somewhat out of touch on this matter.

Upper-case is correct- right?

Answer 1

Method names are case-sensitive, and all registered methods are all upper-case.

(and the W3C really doesn't matter here; what's relevant are RFCs 7230 and 7231).