EDT reads from SYSDTA in the following cases:
When reading lines in L mode if @EDIT ONLY is set or in batch mode. If the line represents an EDT statement then it is executed immediately. Otherwise, the line is stored in the current work file.
When reading with the statement @CREATE ... READ without a prompt or in batch mode.
The records that are to be read from SYSDTA may have a maximum length of 32763 bytes (RDATA permits an input area of 32767 bytes, where the first 4 bytes constitute the record length field).
When EDT is initialized, the SYSDTA character set is determined.
This is used when reading from SYSDTA. If the assignment to SYSDTA changes then the character set is determined again and reading is subsequently performed with the new character set.