Some formats require character encodings that use non-byte-aligned representations. E.g., 7-bit ascii codes that are not each in an octet, but are packed back to back 7 bits each, so that 56 bits stores 8 characters.

Some use USASCII, others, like GSM_338 are more international friendly.

There are not many encodings like this, but they are important in that they are commonly used.

In DFDL v1.0, these must be represented as different encoding names. E.g., this is not USASCII character encoding with some other properties to indicate how the codepoints are packed, it is 'USASCII-packed' or some other variant name.

We need to recognize a variant name and implement 7-bit packed USASCII.