These are intended to be simple tools for interpreting a pattern of coding dots or bars on a cover, which work out the meaning of the dot pattern and state what it corresponded to at which dates, as far as is known. (See this page for an overview of the coding system.) At present there are two tools:
- A translator for the "standard" patterns of c.1973-94 with fourteen dot positions.
- A translator for the "transitional" codes of the 1990s with a pattern of bars, which were used during the switch to OCR/VCS and before 4-state codes came in.
There are also listings of code binaries by page, and the keyings for individual outward codes, so the user may inspect the data being used.
The general idea is that you match the dot (or bar) pattern on your cover by clicking on the appropriate dots/bars to turn them on or off, and the interpretation appears in the box below. "Start" (S) and "format" (F) positions were there to provide fixed points for the machinery to work with and dots/bars are always present in those positions. "Parity" (P) positions were for error checking, and a dot/bar was printed only if needed to make the number of dots/bars in the appropriate part of the pattern even. The parity bars in this tool will be switched on and off automatically. These positions can be a big help when deciding exactly how many spaces there are between dots/bars on a cover ...
Interpretations of other formats may be added later if agreement to use the necessary data can be secured.