[Help-bash] confusion of shell's new option compat41

[Ma Shimiao]

According to changelog and manpage, I find compat as a new option is added.
I have read manpage for many times. But I actually can't find out what it 
affects.
And I don't understand what special character means.

ManPage as follow:
compat41
            If set, bash, when in posix mode, treats a single quote in a dou‐
            ble-quoted  parameter expansion as a special character.  The sin‐
            gle quotes must match (an even number) and the characters between
            the single quotes are considered quoted.  This is the behavior of
            posix mode  through  version  4.1.   The  default  bash  behavior
            remains as in previous versions.

Could someone give me a example shows how to use compat41?

Thanks a lot.