Associators of {Win32_Account : two keys, why ?

[noel]

Hello,
Why the good format of a request wql is :
ASSOCIATORS OF {Win32_Account.Domain='herisson',Name='noel'}
and not
ASSOCIATORS OF {Win32_Account.Name='noel'}

Is it why the class Win32_Account use two keys that i must use these
tow in the associators statement?
I really don't undestand
Thank

Ps : i use wbemtest.exe but i think it's the same thing with a vbs