VISCII was designed by the Vietnamese Standardization Working Group (Viet-Std Group)[1] led by Christopher Cuong T. Nguyen, Cuong M. Bui, and Hoc D. Ngo based in Silicon Valley, California in 1992 while they were working with the Unicode consortium to include pre-composed Vietnamese characters in the Unicode standard.
VISCII, along with VIQR, was first published in a bilingual report in September 1992, in which it was dubbed the "Vietnamese Standard Code for Information Interchange".
[2] The report noted a proliferation in computer usage in Vietnam and the increasing volume of computer-based communications among Vietnamese abroad, that existing applications used vendor-specific encodings which were unable to interoperate with one another, and that standardisation between vendors was therefore necessary.
The successful inclusion of composed and precomposed Vietnamese in Unicode 1.0 was the result of the lessons learned from the development of 8-bit VISCII and 7-bit VIQR.
As is the case with IETF RFCs, RFC 1456 notes them to be "conventions" used by overseas Vietnamese speakers on Usenet, and that it "specifies no level of standard".
There are (short of dropping tone mark support for capital letters, as in VSCII-3) essentially four different ways to handle this problem: VISCII went for the last option, replacing six of the least problematic (e.g., least likely to be recognised by an application and acted on specially) C0 control codes (STX, ENQ, ACK, DC4, EM, and RS) with six of the least-used uppercase letter-diacritic combinations.