|Difference Area||Level 1
Sends ASCII only.
Keystrokes that normally send DEC Supplemental Characters transfer nothing. (Interpreted as an error.)
User-defined keys are do not operate.
Special function keys and six editing keys do not operate (except F11, F12, and F13, which send ESC, BS, and LF, respectively).
|Permits full use of VT220 keyboard.|
|7 or 8 bits||The 8th bit of all received characters is set to zero (0).||The 8th bit of all received characters is significant.|
|Character Sets||Only ASCII, national replacement characters, and DEC special graphics are available.||All VT220 character sets are available.|
|C1 Control Characters||All transmitted C1 controls are forced to S7C1 state and sent as 7-bit escape sequences.||–|