For those entities which desire to use the Exempt Liquidity Market Exchange network for an alternative trading system registered with the SEC on form ATS-N
See https://www.govinfo.gov/app/details/CFR-2012-title17-vol3/CFR-2012-title17-vol3-sec242-301
Broker-Dealers may registered an ATS on the Exempt Liquidity Market Exchange and use their FINRA MPID on Form ATS.