The zoned decimal format is a modification of the EBCDIC format.
The zoned decimal format seems to be a modification to facilitate
processing decimal strings of variable length.
The length of zoned data may be from 1 to 16 digits, stored in 1 to 16 bytes.
We have the address of the first byte for the decimal data,
but need some “tag” to denote the last (rightmost) byte.