Maybe you already had the “joy” to find out that accessing the “Row Selector” column of an updateable tabular form isn’t that straightforward as expected. Because the corresponding g_f01 array isn’t indexed by row number as the other column-arrays of the tabular form.
Instead it contains as many values as you have checked rows. The value of the array entry contains the “real” row number for which it has been checked. So you can have the situation that g_f01 has a count of 2, but your g_f02 containing the EMPNO contains 15 rows. In the case if the g_f02 is your “driving” array, because you want to process all the records and only for the checked ones you want to do something special, it can get really challenging for a new APEX programmer (and even for a more experienced one).