•  What is the EIT wave:                                                     

  some citations:

  EIT WAVES ARE	DIMMINGS CAN BE
  ‘Fast magneto-acoustic linear wave’	‘slow dimmings’
  ‘piston driven shock’, ’blast wave’	‘natural dimmings’
  ‘quasi-circular expanding structure’	'coronal dimmings'
  ‘plasma compression on separatrix’	'chromospheric dimmings'
  ‘snow-plow effect during time-varying reconnection’	'assymetrical dimmings'
  ’nonlinear fast mode...why too slow?’’	'fast dimmings'
  ‘loop opening’	‘stationary dimmming’
  ’expanding footpoints’	‘canalized dimmings’
  ‘waves emitted on the separatrix’	''dimmings without EIT waves'
  ‘stationary fronts’	'secondary dimmings'
  ‘Transient coronal holes'	'angularly-restricted dimmings'
  etc...	etc...

   

•  How many types of EIT waves exist?

•  Classification of events is crucial.

See (Biesecker, D., et al, APJ, 569, 1009, 2002 ) for the first classification of EIT waves by B. Thompson observed in 1997-1998, depending on their probability and magnitude.

See (Hudson S. & Webb D., 1997 AGU Monograph) for the first dimming classification into IV types seen in different wavelengths.