 Defective sectors are recorded at a table in the lead-in (an administrative area) and in a copy of the table in the lead-out.From the host computer's perspective, an MRW disc provides a defect-free block-accessible device, upon which any host supported filesystem may be written.Such filesystems may be FAT32, NTFS, etc., but the preferred format is usually UDF 1.02, as this file format is widely supported.