UPDPTF / DLTPTF

Rob - in another thread you stated:

"I think a command it may be using is UPDPTFINF. I use that quarterly,
along with DLTPTF . . . "

I read the help for UPDPTFINF. It says "This command only needs to be run
during a complete system recovery after library QGPL has been restored."
You always have a reason for what you do, so I'm curious as to why you run
this.

Also, the reason you run DLTPTF. Disk space?

Thanks.