Appendix D: System subdivision

APPENDIX D EXPLANATION

A system subdivision diagram, or often called a product structure diagram, shows the makeup of a project or product.

Appendix D System Subdivision diagram comes from ANSI/ASME Y14.44, Figure 7. At the top of the diagram is the first level labeled “System designation”. Beneath the System designation level is the “Set designation” level. And below the Set designation level are the “Units” that make up the Set. Reference designation assignment begins below the set level, with the units. On my diagram I indicate the complete reference designation prefix at the upper left outside corner of the rectangle for that level.

An example is that Doppler Radar equipment that I worked on when assigned to the Intermediate Maintenance Department onboard the USS Hancock (CVA-19) aircraft carrier when I was in the U.S. Navy. This equipment was used to feed ground speed and drift angle information to an analog navigation computer in an aircraft.

For this piece of equipment the system subdivision diagram would be labeled something like this:

And so on for how far down or how far across you need to go.

Things are simple for a single board project/product though. There is only one unit and so you drop the use of the reference designation prefix “1”.