What does "ze" mean in "R1234ze"

[kaon]

I have seen explainers like https://www.swep.net/refrigerant-han...rigerants/sd6/ and https://www.achrnews.com/articles/10...stem-explained

But have not found any clear explanation of the lowercase "ze" and "yf" commonly seen suffixed in R1234ze and R1234yf.

I understand the uppercase parenthesized (E),(Z) suffixed like R1234ze(E) is used to specifically refer to the (E) isomer.

Does the lowercase "ze" suffix refer to the unspecified mixture of the 2 isomers?

What does "yf" mean?

[RANGER1]

I have seen explainers like https://www.swep.net/refrigerant-han...rigerants/sd6/ and https://www.achrnews.com/articles/10...stem-explained

But have not found any clear explanation of the lowercase "ze" and "yf" commonly seen suffixed in R1234ze and R1234yf.

I understand the uppercase parenthesized (E),(Z) suffixed like R1234ze(E) is used to specifically refer to the (E) isomer.

Does the lowercase "ze" suffix refer to the unspecified mixture of the 2 isomers?

What does "yf" mean?

Should answer your question.
http://hvacrfundamentals.blogspot.co...ering.html?m=1