.SECONDARY vs. .PRECIOUS doc of danger

[jidanni]

You fellows have a lot of explaining to do. (On the Info page, not to me.)

In (info "(make) Special Targets")
`.PRECIOUS'
     ...Also, if the target is an intermediate file, it will not be
     deleted after it is no longer needed, as is normally done... In
     this latter respect it overlaps with the `.SECONDARY' special
     target.

However we see that only genuine .PRECIOUS will preserve the
intermediate file. .SECONDARY, on the other hand, will blow - it - away.

$ ls
Makefile  u.kml
$ cat Makefile
.SECONDARY:%.kmz
%.kmz:%.kml;touch $@
%.val:%.kmz;
$ make u.val
touch u.kmz
rm u.kmz
$ emacs Makefile
$ cat Makefile
.PRECIOUS:%.kmz
%.kmz:%.kml;touch $@
%.val:%.kmz;
$ make u.val
touch u.kmz