Hi, Thanks for clearing up that file size query for me. You are right about that 258 (it's actually 256) header attribute. In that header is where the IMDMP special security option settings are stored (if they are indeed enabled). But the options are rarely ever used by most developers. For more information, download UDCM V2.0 from: http://members.aol.com/DataETRsch/udcm.html and view the help documentation. Also, the 256 byte header itself is encrypted with a 128-bit encryption code. Thanks again! :-) Jeremy... President DataET Research Data Engineering Technologies