Boundary diagrams depict the system and its interfaces with adjacent systems, the environment, and/or the system user. A boundary diagram “cuts” the analysis object free. The interfaces are shown in a categorized form. The most common interface categories are:
P – Physically touching
E – Energy transfer
I – Information transfer
M – Material exchange
Physical clearance (joint pattern) In the same way, the boundary diagram depicts the inherent relationships for the object of analysis.