This license statement is used in two distinct circumstances. Either the software is covered by a license that does not fit into any of the “formally” specified categories, but the catalogue team judges it usable by most users. Otherwise, the software consists of distinct parts to which different (free) licenses apply.
While use is probably safe, each potential user should check the software’s license statement (or statements) before using the software.
Further information about the set of TeX Catalogue License Categories is available.
Modified 2007-11-20 Robin Fairbairns, University of Cambridge