ISO/IEC 10538 defines the control functions, and their coded representations, needed for use in text communication. The coded representations are intended for use when the control functions concerned are embedded in the communicated text, not when they are separated from the text as elements of a communication protocol.
With two exceptions, the control functions of ISO/IEC 10538 have been taken from ISO/IEC 6429 but they have been given more specific definitions than in that standard. The exceptions are the functions PAGE TERMINATOR (PT) and DOCUMENT TERMINATOR (DT). These are alternative names assigned by ISO/IEC 10538 to the control functions INFORMATION SEPARATOR THREE (IS3) and INFORMATION SEPARATOR FOUR (IS4) of ISO/IEC 6429, to represent their correspondingly more specific definitions.
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