Abstract: A method for selectively enabling writing of data multiple times onto a write-once read-many optical disk by a host system, the disk having a disk type indicator, and each sector having a SWF field and a flag field and user data, wherein new data bits replace existing data bits in a one-for-one ratio without mapping, comprising the steps of: reading a disk type indicator; setting a firmware flag allowing writing to the disk if the disk type is erasable WORM; receiving a write command from the host system, the command specifying a sector to write to; reading the contents of the disk SWF and flag fields for the sector; overwriting all user data on the sector with all zeroes if the firmware flag is set; replacing every user data bit in the sector with a zero in a one-for-one ratio without mapping; and resetting the contents of the disk SWF and flag fields to indicate the sector is available for writing.