Packet Type Identifier 
Payload Type Identifier 
Payload Type Indicator 
Pipe Test Insert 
Palomar Testbed Interferometer 
Plugging temperature indicator 
Polskie Towarzystwo Informatyczne 
Power Tool Institute 
Press Trust of India 
Public Technology, Inc. 
pancreatic trypsin inhibitor 
Permanent Trailer Identification 
Permit to Install 
Personal Telecommunication Identity 
Physical Training Instructor 
Polskiego Towarzystwa Informatycznego 
Post-Tensioning Institute 
Power Terrestrial Interface 
Preliminary Test Information 
Primary Terrestrial Interface 
Programmed Test Input 
Public Technology Institute 
Parent Training and Information 
Parent Training and Information center 
Parent Training and Information Center… 
Patni Computer Systems Limited 
Payload Type Identifer 
Penetrating Trauma Index 
PENNSYLVANIA TRANSPORT INSTITUTE 
Performance Technologies Inc.