1. All non-mining areas (no methane).
2. Does not cover Zone 0 areas (covers 1 and 2)
3. IIC (gas) and IIIC (dust) also covers IIB and IIA ratings
4. T4 and T3 are temperature classes that cover LT and LTH ambient ratings respectively.
5. IIC is equivalent to NEC Class 1, Groups A and B.
6. Gb = explosive atmosphere between 10 and 1000 hrs/yr
7. Db = explosive surface between 10 and 1000 hrs/yr
8. For Ex-proof power supply has an IIB rating (lower than the heads) which means no hydrogen atmosphere and is equivalent to NEC Class I, Group C
Atex Guidance Poster (link by kind permission of CML)