File extensions are not always as meaningful as Windows would have you believe. :) But, here are a few relevant docs I found from a simple Google search:

• PROCGI - the .pf file is a configuration file used by this old, scary CGI toolkit for Progress databases.

• filext.com has a few entries for .pf as well. (Looks like a Macintosh thing used by Aladdin Systems software).

• From www.icdatamaster.com:

PF= Progress Parameter File 
PF= Aladdin Systems security software : Private File 
PF= Archive 
PF= Monitor or Printer Profile File 
PF= ICC Profile: Windows ICM profile
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