MarkSpace

R.140 (mark and space)

The 'ITU Recommendation R.140' paragraph 31.37 specifies:

The English term “marking” or “mark” ...

Note 2 – In standardized start-stop telegraphy the term corresponds to the “stop” element.

The English term “spacing” or“space” ...

Note 2 – In standardized start-stop telegraphy the term corresponds to the “start” element.

The conclusion here is: space = startbit, mark = stopbit.

V.11

When the signal condition 0 (space) for data circuits ... is transmitted, the output point A is positive with respect to point B.

When the signal condition 1 (mark) for data circuits ... is transmitted, the output point A is negative with respect to point B.

ISO/IEC 8482

Va' - Vb' <= -0.2V	MARK, 1
Va' - Vb' >= 0.2V	SPACE, 0