What the WORM append file is

You can append data to a WORM append file. The WORM operations are done in 256-KB segments, so that when byte 256KB+1 is written, the previous segment automatically becomes immutable.

It is sometimes useful to have a SnapLock file that accepts appended data. An example would be a log file that you must retain. Rather than filling a log and copying it to a SnapLock file, you can create the file as a SnapLock file, append data to it, and then lock the file in place.