DCSM Device Component Select Mode
Whether editing functions act on the presentation or the data.
CSI 9 h
Mode 9 is the other mode the fifth edition of ECMA-48 added for bidirectional text. A device that reorders text for display has two positions, one in the text as presented and one in the data as stored, and this mode says which one functions such as CR, ICH and EL move or act on.
| State | ECMA-48 calls it | Meaning |
|---|---|---|
Reset, CSI 9 l | PRESENTATION | they act on the presentation component |
Set, CSI 9 h | DATA | they act on the data component |
Neither xterm nor libghostty-vt implements it. Both ignore CSI 9 h and CSI 9 l, and both answer DECRQM with 0, not recognized: the mode is not among the ones xterm’s do_ansi_rqm answers for.
Validation
DCSM-1: Not recognized
\e[9$p
|_____|
reply \e[9;0$y
DCSM-2: Not recognized after it is set, either
\e[9h
\e[9$p
|_____|
reply \e[9;0$y