There are multiple definitions:

1. ejection fraction companion(English)

   • metric that mathematically complements EF
   • EF, FS, FAC, GLS
   • Cardiology, Statistics
   • https://doi.org…ard.2018.06.074
   • https://doi.org…siol.00056.2018

2. electrochemical fuel converter(English)

   • CAES, CCHP, CHR, CNG, CNHC, IDLH, MSDS, STEL, SMES
   • Air pollution, Environment, Occupational disease, Safety and health
   • https://doi.org…OC.2012.2192469