In RS232-C, the "Marking" signal (a
<literal>1
</literal>) is represented by a voltage between -2 VDC and -12 VDC, and a "Spacing" signal (a
<literal>0
</literal>) is represented by a voltage between 0 and +12 VDC. The transmitter is supposed to send +12 VDC or -12 VDC, and the receiver is supposed to allow for some voltage loss in long cables. Some transmitters in low power devices (like portable computers) sometimes use only +5 VDC and -5 VDC, but these values are still acceptable to a RS232-C receiver, provided that the cable lengths are short.