virtual bool is_loadable(const DataFile::CollectionItemTypeBase &, const std::string &) const;
virtual NameList get_names(const DataFile::CollectionItemTypeBase &) const;
virtual void load(DataFile::Collection &, const DataFile::CollectionItemTypeBase &, const std::string &) const;
+ virtual IO::Seekable *open(const string &) const { return 0; }
};