$X

1995 Version of ANSI (Equivalent to Current ISO Version) of Standard

$X has a nonnegative integer value which approximates the value of the horizontal co-ordinate of the active position on the current device. It is initialized to zero by any control-function or format that involves a move to the start of a line.

The unit in which $X is expressed is initially equal to ‘characters’. Certain formats may change this.

When any control-function would leave the cursor in a position so that the horizontal co-ordinate would be uncertain, the value of $X will not be changed. In such cases the value of $Device will be an error-code.

If a Character Set Profile input-transform is in effect, then $X is modified in accordance with the input prior to any transform taking place. If a Character Set Profile output-transform is in effect, then $X is modified in accordance with the output after any transform takes place.

See 8.2.17 (Read command) 8.2.23 (Use command) and 8.2.25 (Write command).