Personal Digital Assistant 
public display of affection 
Patent Ductus Arteriosus 
Principal Development Activity 
Preliminary Damage Assessment 
Personal Digital Assistants 
Pressurized Docking Adapter 
Payload Disconnect Assembly 
posterior descending artery 
Power Distribution Assembly 
Power Driven Arm 
Pregnancy Discrimination Act 
preliminary design approval 
Preliminary Design Audit 
Propellant Drain Area 
Parenteral Drug Association 
patent ductus arteriosis 
Percentage of Defectives Allowable 
personal data assistant 
Personal Display of Affection 
Phase Doppler Analysis 
Photon Detector Assembly 
Portable Diagnostic Analyzer 
Portable Digital Assistant 
post-deposition anneal 
preliminary design acceptance 
preliminary design assessment 
preliminary design authorization 
PROBLEM DETERMINATION AID 
Packaging Distributors Association