Let R°° = dir lim R", the countable direct limit of real lines. We identify R" with R" X {0} C R"+l, so R°° = UneNR". Paracompact (topological) manifolds modeled on R°° are called R°°-manifolds. Aspects of R°°-manifolds have been studied by R. E. Heisey, V. T. Liem, et al. Their works show that the behavior of R00-manifolds is similar to that of /2-manifolds or Q-manifolds (cf. references of [4]).In