'Pervasive operation.' In the doctrine of the Yoga^ca^ra school， the mental function that goes and operates in all places. That is， a function where defilements are not limited to a specific object， but act with all external elements existent in one's own realm or environment. They are always present. This group of elements falls under the general category of caitta （心所） elements， and includes the five elements of volition （作意）， contact （触）， sensation （受）， perception （想） and thought （思）.