ISLOGICAL
Applies to: 
Calculated column
Calculated table
Measure
Visual calculation
Checks whether a value is a logical value, (TRUE or FALSE), and returns TRUE or FALSE.
Syntax
ISLOGICAL(<value>)
Parameters
| Term | Definition |
|---|---|
| value | The value that you want to test. |
Return value
TRUE if the value is a logical value; FALSE if any value other than TRUE OR FALSE.
Remarks
This function is not supported for use in DirectQuery mode when used in calculated columns or row-level security (RLS) rules.
Example
The following three samples show the behavior of ISLOGICAL.
//RETURNS: Is Boolean type or Logical
= IF(ISLOGICAL(true), "Is Boolean type or Logical", "Is different type")
//RETURNS: Is Boolean type or Logical
= IF(ISLOGICAL(false), "Is Boolean type or Logical", "Is different type")
//RETURNS: Is different type
= IF(ISLOGICAL(25), "Is Boolean type or Logical", "Is different type")