Videotex character set


The character sets used by Videotex are based, to greater or lesser extents, on ISO/IEC 2022. Three Data Syntax systems are defined by ITU T.101, corresponding to the Videotex systems of different countries.

Data Syntax 1

Data Syntax 1 is defined in Annex B of T.101:1994. It is based on the CAPTAIN system used in Japan. Its graphical sets include JIS X 0201 and JIS X 0208.
The following G-sets are available through ISO/IEC 2022-based designation escapes:
NameG-set escape type byteISO-IR for byte
Primary Character setSingle byte 94-code0x4A ISO-IR-14
Katakana Character setSingle byte 94-code0x49 ISO-IR-13
Mosaic I setSingle byte 94-code0x33 '
Mosaic II setSingle byte 94-code0x63 ISO-IR-71
Display Control setSingle byte 96-code0x38 '
PDI setSingle byte 96-code0x57 '
MVI setSingle byte 96-code0x39 '
Kanji setMultiple byte 94n-code0x42 ISO-IR-87
Macro setSingle byte DRCS 96-code0x40 '
DRCS I setSingle byte DRCS 94-code0x41 '
DRCS II setMultiple byte DRCS 94n-code0x40

Mosaic sets for Data Syntax 1

The mosaic sets supply characters for use in semigraphics.
� Not in Unicode

Data Syntax 2

Data Syntax 2 is defined in Annex C of T.101:1994. It corresponds to some European Videotex systems such as CEPT T/CD 06-01. The graphical character coding of Data Syntax 2 is based on T.51.
The default G2 set of Data Syntax 2 is based on an older version of T.51, lacking the non-breaking space, soft hyphen, not sign and broken bar present in the current version, but adding a dialytika tonos at the beginning of the row of diacritical marks for combination with codes from a Greek primary set. An umlaut diacritic code distinct from the diaeresis code, as included in some versions of T.61, is also sometimes included.
The default G1 set is the second mosaic set, corresponding roughly to the second mosaic set of Data Syntax 1. The default G3 set is the third mosaic set, matching the first mosaic set of Data Syntax 1 for 0x60 through 0x6D and 0x70 through 0x7D, and otherwise differing. The first mosaic set matches the second except for 0x40 through 0x5E: 0x40 through 0x5A follow ASCII, whereas the remainder are national variant characters; the displaced full block is placed at 0x7F.
Data Syntax 2 is defined in Annex D of T.101:1994. The graphical character coding of Data Syntax 3 is based on T.51.
The supplementary set for Data Syntax 3 is based on an older version of T.51, lacking the non-breaking space, soft hyphen, not sign and broken bar present in the current version, and allocating non-spacing marks for the overline and solidus and several semigraphic characters to unallocated space in that set.
See the comments in the T.51 article for caveats about the combining mark Unicode mappings shown below. Unlike Unicode combining characters, T.51 diacritic codes precede the base character.

C0 control codes

for Videotex differ from ASCII as shown in the table below. The,, , and codes are also available in some or all data syntaxes, but without change in name or semantic from ASCII.
SeqDecHexReplacedSyntaxesAcronymNameDescription
^H0808BS1, 2, 3APBActive Position BackwardMoves cursor one position backward. If it is at the start of the line, moves it to the end of the line and back one line. This retains one possible semantic of the ASCII.
^I0909HT1, 2, 3APFActive Position ForwardMoves cursor one position forward. If it is at the end of the line, moves it to the start of the line and forward one line.
^J100ALF1, 2, 3APDActive Position DownMoves cursor one line forward. If it is at the last line of the screen, moves it to the first line unless Data Syntax 3 scroll mode is active. This retains one possible semantic of the ASCII.
^K110BVT1, 2, 3APUActive Position UpMoves cursor one line backward. If it is at the first line of the screen, moves it to the last line unless Data Syntax 3 scroll mode is active.
^L120CFF1, 2, 3CSClear ScreenResets entire display to spaces with default display attributes and returns the cursor to its initial position. In Data Syntax 1, also resets macros and DRCS. This retains one possible semantic of the ASCII.
^M130DCR1, 2, 3APRActive Position ReturnMoves the cursor to the start of the line. In Data Syntax 3, may instead move it to the start of the active field if it is entirely within it. This retains one possible semantic of the ASCII.
^Q1711DC1/XON2CONCursor OnMakes the cursor visible.
^R1812DC22RPTRepeatRepeats the immediately preceding graphic character a number of times indicated by the low six bits of the following byte.
^T2014DC41KMCKey-In-Monitor ConcealTakes one parameter: 0x40 makes the key-in-monitor area unconcealed, 0x41 makes it concealed.
^T2014DC42COFCursor OffMakes the cursor invisible.
^X2418CAN1, 2, 3CANCancelIn Data Syntax 2, fill the rest of the current line with spaces. In Data Syntax 1 and 3, immediately stop all running macros. Contrast the semantic of basic ASCII.
^Y2519EM1, 2, 3SS2Single Shift Two.
^Z261ASUB3SDCService Delimitor CharacterImplementation-defined but non-presentational.
^\281CFS1, 3APSActive Position SetFollowed by two bytes respectively giving a row and column address in their low six bits. Compare and.
^]291DGS1, 2, 3SS3Single Shift Three.
^^301ERS1, 2, 3APHActive Position HomeReturns cursor to the initial position.
^_311FUS1, 3NSRNon-Selective ResetResets all display attributes, then moves the cursor to a specified position. Followed by two bytes respectively giving a row and column address in their low six bits. Compare.
^_311FUS2APAActive Position AddressFollowed by two or four bytes giving a row and column address in their low six bits. Four bytes are used if there are more than 63 rows and columns, with the most significant six bits being first for each parameter. Compare and. If the following byte is not in the range of 0x40 to 0x7F, indicates a switch to another coding scheme.

C1 control codes

The following specialised C1 control codes are used in Videotex. There are four registered sets, with some differences between them.