Manual:$wgMathValidModes

Math: $wgMathValidModes
To access this at run-time, use MathConfig::getValidRenderingModes(). Do not use the non-normalized configuration directly.
Introduced in version:1.23.0
Removed in version:Still in use
Allowed values:(array)
Default value:[ MathConfig::MODE_SOURCE, MathConfig::MODE_MATHML ] (1.40+)

[ MathConfig::MODE_PNG, MathConfig::MODE_SOURCE, MathConfig::MODE_MATHML ] (1.38-1.39)
[ MW_MATH_PNG, MW_MATH_SOURCE, MW_MATH_MATHML ] (1.24-1.37)

array( MW_MATH_PNG, MW_MATH_SOURCE ) (1.23)