OpType

Values of continuous fields can be used with arithmetic operators.

Nominal field values can only be tested for equality.

Ordinal field values in addition have an order defined.

Not above three types.

The names of the product elements

The name of the type

Tests whether this optype is categorical (nominal or ordinal).

Tests whether this optype is regression (continuous).

Defines const variables could be used in Java. Use Object.XXX() instead of Object.xxx$.MODULE$