In this article, I just wanted to highlight the letter in the P&ID diagram and what it means.

Table below is from a a book called Contrl and Field Instrumentation (ISA) page 17 of the PDF in the Reference section.

Xybernetics Engineering - Instrument Naming Convention ISA

This table is handy for engineers who are trying to assign a tag in a P&ID diagram.

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I am a software developer in Calgary, Alberta, Canada with passion in getting my fingers in any new technology. I started software development when I was 10 years old and have never looked back. Now with well over 35 years of software development, I wanted to share some of these key knowledge with the people of the world in the wide web.