What is the best practice for UE4 material creation?

Hi folks,

As far as I know, Tech artists and graphics SEs connect or code material for artists in UE4. I am not sure how they maintain materils among different version. UE4 stores material in binary format. How can I do code review(material review) based on previous version? Is there any way to save material or convert it to binary to review? Or maybe there is other method to maintain them. Would you introduce your way in real project? Thanks.