NSO is a Neighborhood Stabilization Overlay, which is a type of zoning district adopted by the City of Dallas in 2005. NSOs can regulate things like how much yard space is allowed on all sides of the home, where the garage is located and whether or not it is attached to the home, as well as the height of homes.
La Bajada residents have expressed frustration that the height and size of several new homes in their neighborhood are incompatible, but the La Bajada NSO is not being honored by the city and outside developers.