Sub oscillator usage when using Gazell protocol

To the kind attention of Nordic support team,

We are going to use gazell protocol for some of our wireless products. Could you please point me out to the relevant documentation about how gazell protocol machine gets its time base? Do you recommend the usage of the XL1, XL2 sub oscillator for more precision? I have to say that our device is not going to have power problems, so will it suffice to have the main oscillator and trigger any sort of software correction? In this case is there some change that must be done to the code in order to inform the gazll stack about the timing source?