Честотите се дефинират като: много чести (≥ 1/ 10), чести (≥ 1/ 100 до < 1/ 10), нечести (≥ 1/ 1 000 до < 1/ 100), редки (≥ 1/ 10 000 до < 1/ 1 000), много редки (< 1/ 10 000).
Frequencies are defined as: very common (≥ 1/ 10); common (≥ 1/ 100 to < 1/ 10); uncommon (≥ 1/ 1,000 to < 1/ 100); rare (≥ 1/ 10,000 to < 1/ 1,000); very rare (< 1/ 10,000).