Hi Nordic,
As per the Thread specification 1.3.0 the there are two types of Thread Link implementation as below:

As per the NRF52840 Product Specification v1.8 at-least it seems to support only TL1 i.e. IEEE 802.15.4-2006 standard.

I would like just confirm if this is only link supported on Nordic SoC. Also are TL2 links backward compatible with TL1 links?
Regards
Mohinish Naik