Multiple targets out of one command execution

[Simon Peter]

Hi,

how can I tell Make that one invocation of a command creates multiple
target files? For example, I want something like this:

tcpwndsize.tr tcpwndsize.nam tcp.tr: tcpwndsize.ns
        ns tcpwndsize.ns

Telling Make that "ns" creates the files tcpwndsize.tr, tcpwndsize.nam
and tcp.tr from the file tcpwndsize.ns, all in one run.

When running Make serially, the above fragment already gives the
correct result, but running make in parallel (which I do) results in
multiple (superfluous) invocations of the rule, while Make tries to
create the remaining targets.

Thanks,
Simon