To prepare symbolic debugging with Open Watcom's WD, the assembly source must be assembled with JWasm's -Zi option. Additionally, Open Watcom's linker Wlink or JWlink has to be invoked with switches debug c and option cvp.
Please note that the WD version that we're talking about here is the one that is usually installed in WATCOM\BINW - the DOS version of WD. It should not be confused with the Win32 version of WD in WATCOM\BINNT ( which is just a console version of the Win32 GUI debugger BINNT\WDW ).
WD, debugging a 16-bit DOS application: