Proto-metrisable spaces are elastic

Various notions of point extendable pair-bases are introduced. We prove the following: 1. space is proto-metrisable if and only if it has a unitary point extendable pair-base, and hence proto-metrisable spaces are elastic. ratifiable spaces have weakly point extendable pair-bases. e class of spaces with weakly point extendable pair-bases is closed under the scattering process, and every space with a weakly point extendable pair-base is elastic.