We give some complements to Nitica, V. and Singer, I., 2007, Max-plus convex sets and max-plus semispaces, I. Optimization, 56, 171-205. We show that the theories of max-plus convexity in R n max and B-convexity in R n þ are equivalent, and we deduce some consequences. We show that max-plus convexity in R n is a multi-order convexity. We give simpler proofs, using only the definition of max-plus segments, of the results of loc. cit. on max-plus semispaces. We show that unless is a total order on A, the results of loc. cit. on semispaces cannot be generalized in a natural way to the framework of A n ¼ ðA n , ; Þ, where A :¼ M [ fÀ1g, with M ¼ ðM, ; Þ being a lattice ordered group and À1 a ''least element'' adjoined to M.