Thank you @japiera.
If I may suggest, would it not make sense to have a Global Inventory Sorting setting ---(can be overriden by)---> Product Categories Inventory Sorting setting ---(can be overriden by)---> Product Inventory Sorting setting.
This would make sense where a whole category of products is expirable for example while another category of products would be via FIFO. It would allow a greater deal of flexibility for online shop owners.
Related to this, I'd like to ask what happens in the case that I set the Global default to be BBE/ExpDate and only set the BBE Date on some of the products. For the remaining products (where I do not set a BBE Date value in the inventory), what order would be followed?