Ω(r,θ)/Ω_e =  constant curves inside the stellar envelope of a model star with a global shape generated with an equatorial rotational parameter η_o = 0.8 and a surface differential rotation represented by a Maunder relation with parameter α =  +0.3. All curves were generated with parameters Υ_J,Ω,ϵΩ = 0.3 and 1.6. The iso-rotation curves in a₁) and a₂) correspond to S = S(j²); those in b₁) and b₂) are for S = S(Ω²); the curves in c₁) and c₂) obey the condition S = S(ϖ²Ω²). The solutions are supposed to be valid in the convective zones above the shaded domain.