The Save Ability Formula option from the Item Analysis red triangle menu saves the ability formula to a new column in the data table. This formula can be used to score additional subjects added to the data table or it can be copied to a new table to score a new set of subjects.
The function saved to the data table is called the IRT Ability function. The item parameter estimates are stored in a matrix in this function. For more information about this function, see Help > Scripting Index.