Neutral direct-current telegraph system

{{notability|date=July 2020}}

In telecommunications, a neutral direct-current telegraph system (single-current system, single-current transmission system, single-Morse system) is a telegraph system in which (a) current flows during marking intervals and no current flows during spacing intervals for the transmission of signals over a line, and (b) the direction of current flow (electric polarity) is immaterial.{{Citation|last=Weik|first=Martin H.|title=neutral direct-current telegraph system|date=2001|work=Computer Science and Communications Dictionary|pages=1096|editor-last=Weik|editor-first=Martin H.|place=Boston, MA|publisher=Springer US|language=en|doi=10.1007/1-4020-0613-6_12302|isbn=978-1-4020-0613-5}}