missed backslash after brace expansion {Z..a}

[Andrei Enshin]

Hello,

I’m plaing with brace expansion and can observe some strange (it seems to me) 
behaviour — there is no back slash in the following expansion:
$ echo {Z..a}
Z [  ] ^ _ ` a

however there is an extra space:
$ echo {Z..a} | xxd
00000000: 5a20 5b20 205d 205e 205f 2060 2061 0a    Z [  ] ^ _ ` a.


I expect baskslash just because the output looks like ascii. I may be wrong. 
Would be great if someone can explain which alphabet is used instead.


Documentation says:
«When characters are supplied, the expression expands to each character 
lexicographically between x and y, inclusive, using the default C locale»
https://www.gnu.org/software/bash/manual/bash.html#Brace-Expansion


What is the reason to have extra space instead of backslash?
 
Andrei Enshin