What does ACTVTY stand for?

Activity

A measure of the chemical potential of a substance, where the chemical potential is not equal to concentration, that allows mathematical relations equivalent to those for ideal systems to be used to correlate changes in an experimentally measured quantity with changes in chemical potential. or A time interval in a scheduling problem. Typical examples include the filling or emptying of capacity resources such as tanks or inventories, or the use of physical resources such as trucks, machines, or people