How many metal covered holes are allowed?

I put this question to the answer guys at APA--The Engineered Wood Associaiton and got the following guidelines:

1) If the hole is 6-inches or less we are not too concerned.
2) If the hole is larger than 6-inches we would suggest structural blocking, located adjacent to the hole edge closest to the unsupported panel edge. Blocking should be parallel to the unsupported panel edge.
3) If the edge of a hole 6-inches or larger is less than 24-inches from an unsupported panel edge we suggest following the panel edge support recommendations for narrow width roof sheathing as provide in APA Technical Note R275 (copy attached).
4) Any hole with any dimension larger than the distance between supports should be engineered.

These are just suggestions or guidelines and are based on the assumption that no additional loads are associated with the opening (e.g., an HVAC unit supported by roof sheathing).

Another question is what happens to the poor individual who happens to step on the roofing over the hole?

Thank you, Mr. Drorbaugh. I've been wanting to know the code on that.

These are just suggestions or guidelines and are based on the assumption that no additional loads are associated with the opening (e.g., an HVAC unit supported by roof sheathing).

What are those metal rods coming down from the ceiling of the roof?

Are you referring to the sheathing when you are using the term unsupported panel edge?