# File lib/ole/types/property_set.rb, line 115
      def load_header str
        @signature, @unknown, @os_id, @guid, @num_sections = str.unpack HEADER_PACK
        # should i check that unknown == 0? it usually is. so is the guid actually
        @guid = Clsid.load @guid
        @os = OS_MAP[@os_id] || Log.warn("unknown operating system id #{@os_id}")
      end