Photons may occur in the form of x-rays, gamma rays, or quanta of light. The energy (E) of a photon is expressed as the product of its frequency (v) and Planck's constant (h), as in the equation E = hv. X-ray photons occur in frequencies of 10 18 to 10 21 Hz and energies that range upward from 1 KeV.
Confidence votes 52.5K. In the US, the standards called General Industry Standards are the OSHA standards at 29 CFR 1910 and are sometimes called Part 1910.
1 Standard Industrial Classification Codes (SIC Codes) identify the primary line of business of a company. It is the most widely used system by US government, public, and private organizations.  North American Industry Classification System (NAICS Codes) is the alternative code structure, updated every 5 years.