Experimentally, the pore volume is routinely determined from the adsorption isotherm for nitrogen at 77 K or argon at 87 K using the Gurvich Rule. Therefore, a large number of these low-temperature characterization isotherms are available in the NIST-ISODB: for 291 of the 569 matched adsorbents at least one characterization isotherm is reported. This ratio is slightly higher than in the NIST-ISODB overall but it still forces us to exclude a substantial number of MOFs, and for the future of the NIST-ISODB we suggest placing additional focus on providing these key characterization data in digital form.