questions about "register"

Register is simply a type of the language appropriate to a situation or circumstance.  It includes characteristic vocabulary, sentence structure and level of formality or politeness.  Nonfiction writings are one general register (with separate registers for e.g. popular nonfiction and academic nonfiction).  Another, spoken, register is that used at home with one's family.

Yes, I would say that the names of the colours would appear in the same register (though they would likewise appear together in many registers-- brown, yellow and red are quite average words.  On the other hand, colour words like puce, ultramarine and umber might appear together in different registers.

Cambridge University Press uses four levels or registers of language:  "R3 designates a high degree of formality,  R2 is neutral, R1 colloquial, and R1* vulgar, to be used with care."  They recognize that particular words do not always belong entirely in one category, and may be used in more than one, such as R3-R2 or R2-R1 words.
I have also seen decimal versions of this system, for example, saying that a certain word is in register 2.4 or in register 1.6.

CJ

<I have also seen decimal versions of this system, for example, saying that a certain word is in register 2.4 or in register 1.6.>

I like the scalar way of looking at register.

CalifJim wrote:

I like the scalar way of looking at register. You mean using only integers as values, I assume?  (2.6 is a scalar.) CJ

Not only. I mean any way of looking at formal to informal register in a stepped way instead of only having the formal or informal view. Like a ladder (scalaris/scalae) etc.