Upwd is located in:
unix/src/hpux-7-0/Upwd.i3
unix/src/sunos-4-x/Upwd.i3
unix/src/aix-ps2-1-2/Upwd.i3
unix/src/osf-1.generic/Upwd.i3
unix/src/freebsd-2/Upwd.i3
unix/src/linux/Upwd.i3
unix/src/ibm-4-3/Upwd.i3
unix/src/ultrix-3-1.generic/Upwd.i3
unix/src/aix-3-2/Upwd.i3
unix/src/irix-5.2/Upwd.i3
unix/src/solaris-2-x/Upwd.i3
unix/src/freebsd-1/Upwd.i3
unix/src/sysv-4.0/Upwd.i3