If you set this flag, "Inheritable Parameters" will automatically un-escape "%xx" substrings into their respective 8-bit char; where xx is a hexadecimal number. The translation will use UTF-16 for the unencoded bytes and CP-1252 / ISO-8859-1 for the encoded bytes.
This is necessary, because the Jenkins CLI can't handle assignment of the "=" character (%3d) properly and truncates at the first such char.