Sets the obliquing angle of letters in range ±1.48335 radians (±85°) (DXF 50). A positive angle leans the letters clockwise (to the right). A negative value leans the letters counterclockwise (to the left). A negative value is converted to its positive equivalent by adding the value 2*PI. The initial value is 0.0 by default. 

Example of Working with the Text Style Record Object 

Specific Properties of Text Styles 

OdDbTextStyleTableRecord::obliquingAngle() method