| univariate mixture |  |  | 
| "E" | = | equal variance  (one-dimensional) | 
| "V" | = | variable variance (one-dimensional) | 
| multivariate mixture |  |  | 
| "EII" | = | spherical, equal volume | 
| "VII" | = | spherical, unequal volume | 
| "EEI" | = | diagonal, equal volume and shape | 
| "VEI" | = | diagonal, varying volume, equal shape | 
| "EVI" | = | diagonal, equal volume, varying shape | 
| "VVI" | = | diagonal, varying volume and shape | 
| "EEE" | = | ellipsoidal, equal volume, shape, and orientation | 
| "EVE" | = | ellipsoidal, equal volume and orientation (*) | 
| "VEE" | = | ellipsoidal, equal shape and orientation (*) | 
| "VVE" | = | ellipsoidal, equal orientation (*) | 
| "EEV" | = | ellipsoidal, equal volume and equal shape | 
| "VEV" | = | ellipsoidal, equal shape | 
| "EVV" | = | ellipsoidal, equal volume (*) | 
| "VVV" | = | ellipsoidal, varying volume, shape, and orientation | 
| single component |  |  | 
| "X" | = | univariate normal | 
| "XII" | = | spherical multivariate normal | 
| "XXI" | = | diagonal multivariate normal |