NOVELTY - The porous membrane comprises a layer of porous polymer film made by a dry stretch process including the steps of: extruding a polymer into single layer nonporous precursor; and biaxially stretching the nonporous precursor, and nonwoven, woven or knit layer bonded to a side of the porous polymer film. The biaxial stretching includes a machine direction stretching, transverse direction stretching and a transverse direction relax. The transverse direction stretching includes a simultaneous controlled machine direction relax.    USE - The porous membrane is useful in a filtration membrane, a humidity control membrane, a gas and/or liquid separation membrane, a selective passage of humidity and blockage of liquid water membrane and a multi-layered membrane structure, and a battery separator (all claimed), where the porous membrane is microporous membrane and a thin, pliable, polymeric sheet, foil or film useful in flat sheet membranes, biaxially oriented porous membranes, biaxially oriented microporous membranes, biaxially oriented macroporous membranes, hollow fibers, air-filter cartridge, mass transfer membranes, pressure regulators, medical devices, separators for electrochemical storage devices and fuel cells.    ADVANTAGE - The porous membrane can be efficiently and economically manufactured with high charge density, porosity and stability, increased transverse direction tensile strength, improved hydro-head performance, enhanced physical strength properties, uniform flow rate, excellent moisture vapor transport and reduced gurley and without loss of desirable membrane features.    DETAILED DESCRIPTION - The porous membrane comprises a layer of porous polymer film made by a dry stretch process including the steps of: extruding a polymer into single layer nonporous precursor; and biaxially stretching the nonporous precursor, and nonwoven, woven or knit layer bonded to a side of the porous polymer film. The biaxial stretching includes a machine direction stretching, transverse direction stretching and a transverse direction relax. The transverse direction stretching includes a simultaneous controlled machine direction relax. The machine direction stretching of the biaxial stretching includes the step of transverse direction stretching with simultaneous machine direction stretching. The biaxially stretching of the nonporous precursor includes the machine direction stretching, an additional transverse direction stretching with simultaneous machine direction stretching, and a transverse direction relax. The dry-stretch process includes the step of machine direction stretching to form a porous intermediate before to the biaxial stretching, machine direction stretching followed by the biaxial stretching including the transverse direction stretching with simultaneous controlled machine direction relax, and a second transverse direction stretching with simultaneous machine direction stretching followed by transverse direction relax. The porous polymer film has a round shaped pores, a porosity of 65-90%, a ratio of machine direction tensile strength to transverse direction tensile strength of 1-5, a gurley of less than 20, a mean flow pore diameter of 0.05 microns, an aquapore size of 0.08 microns, a hydro-head pressure of greater than 145 psi, a thickness of 8 microns, a transverse direction tensile strength of 300 kgf/cm2, a standard deviation of mean flow pore diameter of less than 0.05 microns, a water intrusion pressure of 80 psi, a water vapor transmission rate of 8000 g/m2-day, and a transverse direction shrinkage of less than 3% at 120 degrees c. The nonporous precursor is: a blown film and/or a slot die film; and single layer precursor formed by single layer extrusion and a multilayer precursor formed by coextrusion and/or lamination. The membrane has round shaped pores, a porosity of 40-90%, a ratio of machine direction tensile strength to transverse direction tensile strength of 0.5-5, a gurley of less than 100, a mean flow pore diameter of 0.04 microns, an aquapore size of 0.07 microns, and a hydro-head pressure of greater than 140 psi. The round shaped pores have an aspect ratio of 0.75-1.25 and/or a sphericity factor of 0.25-8. The biaxially stretching step of the dry-stretch process includes the simultaneous biaxial stretching of separate, superimposed, layers or plies of nonporous precursor, where none of the plies are bonded together during the stretching process, and includes the simultaneous biaxial stretching of bonded, superimposed, layers or plies of nonporous precursor, where all of the plies are bonded together during the stretching process. An INDEPENDENT CLAIM is included for a battery separator.    DESCRIPTION OF DRAWING(S) - The diagram shows a scanning electron microscope surface photograph of a membrane.