Dump9660 is a tool for creating ISO 9660 compliant CD images suitable
for use with tools such as FreeBSD's burncd.  Dump9660 supports the El
Torrito bootable CD and Microsoft Joliet extensions as well as the
Rock Ridge and Plan 9 system use extensions. Mk9660 is a front end for
dump9660 that provides the traditional ability to create CD images
from a subtree of the file system.  Dump9660 is similar in
specification, but creates and updates backup CD images in the style
of the Plan 9 dump file system.  The dump is file-based rather than
block-based: if a file's contents have not changed since the last
backup, only its directory entry will be rewritten.

- William Josephson and Russ Cox