I just noticed that our make(1) supports VPATH, but is not documented. OK?
Index: make.1 =================================================================== RCS file: /cvs/src/usr.bin/make/make.1,v diff -u -p -r1.141 make.1 --- make.1 10 Aug 2023 10:56:34 -0000 1.141 +++ make.1 25 Oct 2023 10:45:32 -0000 @@ -832,6 +832,10 @@ It should not be used; see the section below. .It Va .VARIABLES List of all the names of global variables that have been set. +.It Va VPATH +A colon separated list of directories appended to the search path (see +.Va .PATH ) . +Supported for compatibility with other implementations. .El .Pp Variable expansion may be modified to select or modify each word of the
