This is documented in R23 Accessory Guidelines document, §15 https://developer.apple.com/accessories/Accessory-Design-Guidelines.pdf

Thank you for the quick follow-up. The descriptor is as follows: 05 0d 09 05 a1 01 85 14 09 22 a1 02 95 02 75 01 15 00 25 01 09 47 09 42 81 02 95 01 75 03 25 07 09 51 81 02 95 01 75 03 81 01 95 01 75 08 26 ff 00 09 30 81 02 a4 05 01 55 0e 65 11 95 01 75 10 26 d0 07 35 00 46 2e 04 09 30 81 02 26 e8 03 46 9e 02 09 31 81 02 b4 c0 09 22 a1 02 95 02 75 01 15 00 25 01 09 47 09 42 81 02 95 01 75 03 25 07 09 51 81 02 95 01 75 03 81 01 95 01 75 08 26 ff 00 09 30 81 02 a4 05 01 55 0e 65 11 95 01 75 10 26 d0 07 35 00 46 2e 04 09 30 81 02 26 e8 03 46 9e 02 09 31 81 02 b4 c0 09 22 a1 02 95 02 75 01 15 00 25 01 09 47 09 42 81 02 95 01 75 03 25 07 09 51 81 02 95 01 75 03 81 01 95 01 75 08 26 ff 00 09 30 81 02 a4 05 01 55 0e 65 11 95 01 75 10 26 d0 07 35 00 46 2e 04 09 30 81 02 26 e8 03 46 9e 02 09 31 81 02 b4 c0 75 03 25 03 09 54 81 02 75 01 25 01 05 09 09 01 81 02 95 01 75 10 27 ff ff 00 00 47 ff ff 00 00 55 0c 66 01 10 05 0d 09 56 81 02 65 00 55 00 85 15 09 55 15 00 25 03 75 03 95 01 b1 02 09 59 25 01 75 01 b1 02 75 04 b1 01 c0 05 0d 09 0e a1 01 85 16 09 52 15 00 25 03 75 03 95 01 b1 82 75 05 b1 01 85 17 09 57 09 58 25 01 75 01 95 02 b1 82 95 06 b1 01 c0 Let me know if you need further clarification.

I have also attached a copy with comments. hid_tp_descriptor.txt