http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Methods of testing large capacity displacement meters
pt. 1. Low pressure flow prover (pipe tap) -- pt. 2. Low pressure flow prover (flange tap) -- pt. 3. Transfer provers -- pt. 4. Critical flow prover.
Transmission Measurement Committee report ; no. 6
American Gas Association, 1515 Wilson Boulevard, Arlington VA 22209