I assume you mean learned code format. The RC5 format uses a toggle bit, meaning a bit that changes upon every press. Using the learned code format that bit remains the same, so if the device dosen't ignore the toggle you could not use the same key twice, i.e entering 11 would be a problem or using a channel command multiple times in a row. These are the channel commands:

RC5 Device: 27 Function: 80 Toggle: 0 Channel +
0000 0073 0000 000A 0040 0020 0020 0040 0020 0020 0040 0040 0020 0020 0040 0040 0040 0020 0020 0020 0020 0020 0020 0CC1
RC5 Device: 27 Function: 81 Toggle: 0 Channel -
0000 0073 0000 000A 0040 0020 0020 0040 0020 0020 0040 0040 0020 0020 0040 0040 0040 0020 0020 0020 0020 0040 0020 0CA1

From the 5000 code 001B(27 decimal) is the device number and 0050/0051(80 and 81 decimal) is the command/function number- you can then enter the device number and function number spread into Make Hex(PC) or IRUtilities(Mac), using the RC5 irp in Make Hex or choosing RC5 in IRUtilities, to make the RC5 learned code version. I also seem to remember a utility where you entered the 5000 code and it gave you learned code format.

dwg