I'm not sure the answer is correct.
If you are scanning and the radio stops on a channel, and you then press "MAN" the upper left display will show the scan list to which the channel has been mapped or one of the scan lists to which the channel has been mapped, if it is mapped to more than one. This display takes the form of, for example: 02-0436. Parsed: Object No. 0436, which is mapped to Scan List No. 2 (and possibly others as well).
The reason that the first three characters ("02-" in my example) when the radio stops on a scanned channel is because it is replaced by "SCN," apparently denoting that the radio is in scan mode (even though it is stopped on one channel).
Whether this display is a good or bad idea, it is a matter of the programmer's choice, not necessity.
It is worth observing that, in the event I understand the metaphor of the PSR-500, it is different from other "scanners" with which folks may be familiar. A slot is a scan list is not, in this radio, the memory location of channel data. Rather it is a vector table, to which the processor directs itself when scan is invoked. In this respect, the -500 metaphor is much closer to the way the scan function operates in current model Motorola portable two-way radios. The fact that one channel might be mapped to two or more active scan lists does not mean that it is scanned multiple times per cycle.