B-L global symmetry in the grand unification theories

Question

- What are the precise [B-L (baryon - lepton) global symmetry](https://en.wikipedia.org/wiki/B_−_L) in the standard model?

- Is this a U(1) global symmetry or a discrete finite group $\mathbb{Z}/N$ global symmetry for the following examples?

Does the precise B-L global symmetry present in: 

- [SU(5) Georgi–Glashow model grand unification theory](https://en.wikipedia.org/wiki/Georgi–Glashow_model)? If so, how does the B-L global symmetry  act on the fermion representations $\bar{5}$ and $10$?

- [SO(10) grand unification theory](https://en.wikipedia.org/wiki/SO(10)_(physics))? If so, how does the B-L global symmetry  act on the fermion's spinor representations $16$?