88 PDF definitions

Portable Document Format 
Policy Decision Function 
probability density function 
Precision Direction Finding 
probability distribution function 
Program Development Facility 
Parkinson's Disease Foundation 
Processor Defined Function 
Pocket Dosimeter, FEMA 
pair distribution function 
plant design factor 
Portable Document File 
Printer Definition File 
Package Definition File 
Panama Defense Force 
Panamanian Defense Force 
parameterized diastolic filling 
Payload Data Formatter 
peritoneal dialysis fluid 
point-detonating fuze 
Portable Data File 
Portable Data Format 
Portable Document Files 
Powder Diffraction File 
Power Density Function 
Power Distribution Frame 
Precision Direction Finder 
Preparation and Development Facility 
Principal Direction of Fire 
Printer Description File