What does ESX stand for?

Essex Arms - NCIC firearms make code (NCIC)

Essex Bancorp, Inc. - AMEX symbol (SPSG)

Essex Co., Ltd., Camden, NJ - Manufacturer code for watercraft hull identification number (USCG)

Essex County College, Newark, NJ - OCLC symbol (OCLC)

Essex Junction, VT - Amtrak rail station code

Extended Systems Executive (SAUS)

Essex (SAUS)