An indicator variable is a special kind of column that takes a value or either 0 or 1. Its value is derived from an underlying expression; the value is 1 if the expression is true for a particular record, and 0 otherwise.
Expressions can have an unlimited number of conditions that can use any of the table’s columns. Indicator variables might be used to identify records with values meeting a certain threshold, or records with certain combinations of values.
If an indicator variable is used as the outcome variable of a model, you can choose to model it with a probit, logit, or linear model. Indicator variables can be summed and tabulated like numeric columns, but in general are not first-class numeric columns.