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).
Esinemissagedus defineeritakse: väga sage (≥ 1/ 10); sage (≥ 1/ 100 kuni < 1/ 10); aeg- ajalt (≥ 1/ 1000 kuni < 1/ 100); harv (≥ 1/ 10000 kuni < 1/ 1000).