In telecommunications and character encoding, the term cancel character refers to a control character which may be either of:

  1. "CAN", "Cancel", U+0018, or ^X used to indicate that the data with which it is associated are in error or are to be disregarded. Exact meaning can depend on protocol. For example:
    • In some journalistic text transmission formats, it signifies that the preceding word should be deleted; it is sometimes called "Kill Word" ("KW") in this context.[1]
    • In some Videotex formats, it stops any running macros.[2][3] In others, it clears the current line after the cursor position (compare EL).[4]
  2. "CCH", "Cancel Character", U+0094, or ESC T used to erase the previous character. This character was created as an unambiguous alternative to the much more common backspace character ("BS", U+0008), which has a now mostly obsolete alternative function of causing the following character to be superimposed on the preceding one.

References

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  1. ^ International Press Telecommunications Council (1976-03-25). Control set for newspaper text transmission (PDF). ITSCJ/IPSJ. ISO-IR-26.
  2. ^ CCITT (1987-07-31). Primary Control Set of Data Syntax I of CCITT Rec. T.101 (PDF). ITSCJ/IPSJ. ISO-IR-132.
  3. ^ CCITT (1987-07-31). Primary Control Set of Data Syntax III of CCITT Rec. T.101 (PDF). ITSCJ/IPSJ. ISO-IR-135.
  4. ^ CCITT (1987-07-31). Primary Control Set of Data Syntax II of CCITT Rec. T.101 (PDF). ITSCJ/IPSJ. ISO-IR-134.