REGIN and REGOUT pins on W7500P

Hello! We have a question about W7500P crystal. There is an input of REGIN and REGOUT. For what they can be used??? To W7500 Datasheet Manual v1.1.1 about it it is written nothing.

Please refer to the following link.

First, please refer to Data Sheet in

Second, refer to Pin Description in


Thanks for your answer.