This reports how many input control signals for this port appear in the paraInSigTable, i.e., only the signals the device's software can actually detect and considers useful to monitor. An admin uses this to know how many rows to expect for this port when walking the input signal table, since not every physical signal line is necessarily exposed via SNMP. For example, if paraPortInSigNumber reports 5 for a port, the admin should expect to find five corresponding paraInSigEntry rows, such as power, online, busy, paperout, and fault, indexed to that port.