Several extensions and modifications have been appended to the original AON
method. Lags allow the project planner to more closely replicate the actual conditions
found in practice. The use of lags can result in the start or finish of an activity
becoming critical. Some computer software simply calls the whole activity
critical rather than identifying the start or finish as being critical. Caution should
be taken to ensure that lags are not used as a buffer for possible errors in estimating
time. Finally, hammock activities are useful in tracking costs of resources used
for a particular segment of a project. Hammock activities can also be used to
reduce the size of a project network by grouping activities for simplification and
clarity. All of the discussed refinements to the original AON methodology
contribute toward better planning and control of projects.