This integer is a bitmask where each bit indicates whether a specific optional, chargeable feature is enabled on the NAC module in this slot, since the description explicitly says it uses individual bits for NAC-specific feature enable status. An admin cares about this because these are typically licensed add-on features tied to the uchasSlotFeKey mechanism elsewhere in this table, so this field is how a management tool audits which paid features are actually active per card without asking the customer's memory. For example, if bit 0 of this integer represents 'compression enabled' and bit 2 represents 'V.90 enabled', a returned value of 5 (binary 101) would tell the admin both features are active on that specific NAC.