> Completion should be specified in the binary, and compatible with all shells This is somewhat like the approach that DEC took with VAX/VMS in the late 1970'

> Completion should be specified in the binary, and compatible with all shells This is somewhat like the approach that DEC took with VAX/VMS in the late 1970's. The command line and arguments/parameters were declared external to the executable and known to the the shell (in this case, DCL) via the SET COMMAND command. It had its own little data description language. The shell did the parsing user interaction (recall, completion, etc) and provided utility functions to the binary to call to obtain params. So while the completion was not technically in the binary, a standard api was used to obtain it and the definitions were created side by side. Worked very nicely and was extensible by 3rd parties and could be used to incorporate "foreign" binaries as well.