EDT only ever permits character sets which are supported by the current XHCS installation. The necessary conversions are handled via XHCS and the properties of the characters (uppercase/lowercase, special characters) are provided by XHCS.
In compatibility mode, there are further restrictions due to VTSU. The only 7-bit character set permitted by EDT is EDF03IRV even if others, for example e.g. EDF03DRV, are defined in XHCS since EDF03IRV is the only 7-bit character set that can be used to communicate with terminals.
This restriction also applies in batch mode. Furthermore, only EBCDIC character sets are permitted, not ISO character sets. If EDT communicates with a terminal then the character set must be compatible with it. In contrast, all the 8-bit EBCDIC character sets are permitted in batch mode.
EDT accepts all input even if the characters/bytes do not form part of the recognized code. All bytes with codes which are not present in the current character set are displayed as smudge characters at the terminal.
They are ignored during lowercase/uppercase conversion and should not be used as special characters such as tab characters (however, there is no mechanism to prevent this). However, they are not (usually) modified by EDT.
Unicode character sets and ISO character sets are not permitted in compatibility mode.