<Li> optimistic time: the minimum possible time required to accomplish an activity (o) or a path (O), assuming everything proceeds better than is normally expected </Li> <Li> pessimistic time: the maximum possible time required to accomplish an activity (p) or a path (P), assuming everything goes wrong (but excluding major catastrophes). </Li> <Li> most likely time: the best estimate of the time required to accomplish an activity (m) or a path (M), assuming everything proceeds as normal . </Li> <Li> expected time: the best estimate of the time required to accomplish an activity (te) or a path (TE), accounting for the fact that things don't always proceed as normal (the implication being that the expected time is the average time the task would require if the task were repeated on a number of occasions over an extended period of time). </Li>

The commonly used network techniques other than pert and cpm are as follows