Doing a google search for 'alien man page', I found this page
, though it didn't say what version of alien it's from.
Here's a few excerpts:
PACKAGE FORMAT NOTES
rpm For converting to and from rpm format the Red Hat Package Manager must be installed.
will convert all the files you pass into it into all the output types you specify. If no output type is specified, it defaults to converting to deb format.
The list of package files to convert.
Make debian packages. This is the default.
Make rpm packages.
Here are some examples of the use of alien:
alien --to-rpm package.deb
Convert the package.deb into a package.rpm