net vs gross hp

doin my college research on the history od camaros. can somebody please tell me the difference between net and gross hp. in 71 they started rating hp as net along with gross and 72 went to net all toeather. id appreciate it if somebody could explain it to me. thanks.

The earlier Gross HP rating was without all the accessories (A/C, power steering, etc.) and usually with headers and modified exhaust. The later Net ratings were with all the accessories on the engine as it would be in the car, including the exhaust system the car would run with. Both were taken at the crankshaft.

Jody

aaaah that makes sense. thanks for the help.