In our continuation of the use of the many diagnostic tools available within the software environment we present you with more information on the Call Structure tool. In this lesson, we begin discussing a task that we are going to undertake for upgrading a petrochemical plant. We give you some background on the products produced in the plants and get you familiar with some of the documents that are typically used when working within the industry. Those documents include Piping/Process and Instrumentation Diagrams or P&ID’s and I/O lists. The P&ID’s give you a pictorial reference of the process and instruments involved while the I/O list acquaints you with instrument information such as signal types, signal ranges and the like. Jump right in and get started on this informational lesson.