RSLogix 500: "FILE N12:24 LEN:5 - FLL - File #10 - 8"

I'm troubleshooting this machine in the field right now. The discrete outputs of this Micrologix 1500 are wired to discrete inputs of a Siemens S7-200. On the MicroLogix, three of the outputs on the drawing are labeled as BCD 1, BCD 2, BCD3, which are the first three bits of N12:24. All I can come up with for "BCD" is binary coded decimal... not sure about that, but it would make sense. Any thoughts? I suspect this is telling the S7 (slave) what pattern to follow, but it's just a hunch.

I looked in the cross reference to see where N12:24 originates and I see "FILE N12:24 LEN:5 - FLL - File #10 - 8". Hmmm.... I don't know what that is. Thoughts?

OMG... "Fill file" Never seen that before.

I figured FLL out... I should have figured it out earlier. Len: 5 was just "length". Nothing weird... it was just re-setting the machine by filling 0s into all the number bits. Sorry... I've been staring at this too long.

I'm still thinking about BCD, though.

I have seen this done many times, it's usually a simple way to sent limited data to another PLC 3 bit BCD = 0-7 decimal 4 bit = 0-15 8 bit = 0- 256 so it could be sending a range of 0-7 for example recipe number but limited to 7 or some other function. Another example is the Mitsubishi VFD's have 3 inputs to control the speed as well as analogue, the 3 inputs are designated as low med high, however by setting these as binary numbers you actually get 7 speeds.
I have even used a 16 way digital output card as crude communications to another PLC (many years ago before communications were limited) 8 bits were used as address & 8 bits as data, it was slow but worked well.