A filter may modify a character but only if it accepts it. Filters are linked to one another in a chain as sources and sinks . The first filter in a chain has stdin as its source. The last filter in a chain has the null object as its sink. Arg1 becomes the source buffer to receiver.
Returns TRUE until no more characters to process.
The sink buffer is informed to not expect any more. Calls getItem to provide filter with an accepted item. Returns TRUE until no more characters to process. If it returns TRUE then Arg1 may have been modified. The capsFilter accepts all characters but converts to upper case, all lowercase characters.