From Pete Crosby of HP:

A file is quarantined when subsystem dump is enabled and a problem with the structures related to an open file is encountered. A subsystem dumpfile is created and the file is then quarantined, which allows only READ access to the file.

FSCHECK has 2 new commands as of 5.5:

QPURGE -- will purge file objects in quarantine

QDISPLAY -- will display information regarding file objects in quarantine.

Other than reading the data and creating a new file, I don't believe the original file can ever be made write-accessible again.

All of this is designed to allow a more resilient system and reduce the number of system aborts, where possible.