Receiving mapped data

Formatted screens are as important for input as for output. Data entry applications are an obvious example, but most other applications also use formatted input, at least in part.

On input, BMS does for you approximately the reverse of what it does on output: it removes device control characters from the data stream and moves the input fields into a data structure, so that you can address them by name.

Maps can be used exclusively for input, exclusively for output (the case we have already covered), or for both. Input-only maps are relatively rare, and we cover them as a special case of an input-output map, pointing out differences where they occur.