We are running ADSM V3R1 on OS/390 2.4

In the documentation for the DELETE VOLHISTORY command
the ADSM V3R1 MVS Admin Ref says:
"Use the DELETE VOLHISTORY command to delete 
sequential volume history information collected by the 
server when the information is no longer needed."

I understand the purpose of the TYPE=DBB records
in the ADSM VOLHISTORY file and that they can be 
deleted when they refer to obsolete database backups.
What about the  other records , e.g. those  with 
TYPE=STGNEW or TYPE=STGDELETE, etc?
When is it safe to delete these records?