RSTS emulation in a browser (now "FILMGR")

[John Foust]

Another RSTS question.  One of my rescued tapes has only several
files with the extension ".FLB"  Compared to other files of the
sets, these are relatively large... up to a meg or so.

In a text file on another related tape, a manager wrote "Learn 
how to use FILMGR, which is invoked by DO FILMGR. It keeps 
storage space down."

Sounds like archiving and compression.  Google is no help.
I looked at DECUS RSTS lists and didn't see it.

Does anyone remember a program called FILMGR for RSTS/e 7
circa 1982?  Does "FLB" mean "file library"?

- John