  We completely characterize definable linear orders in o-minimal structures
expanding groups. For example, let (P,<_p) be a linear order definable in the
real field R. Then (P,<_p) embeds definably in (R^{n+1},<_l), where <_l is the
lexicographic order and n is the o-minimal dimension of P. This improves a
result of Onshuus and Steinhorn in the o-minimal group context.
