Guidelines for Examination - Table of Contents   PART C GUIDELINES FOR SUBSTANTIVE EXAMINATION   CHAPTER II CONTENT OF A EUROPEAN PATENT APPLICATION (OTHER THAN CLAIMS)   CHAPTER II Annex UNITS RECOGNISED IN INTERNATIONAL PRACTICE AND COMPLYING WITH RULE 49(11) (see II,...       1. SI units and their decimal multiples and submultiples     1.2 Other SI units   1.2.1 Supplementary SI units

Definitions of supplementary SI units:

- Plane angle unit

The radian is the plane angle between two radii of a circle which cut off on the circumference an arc equal in length to the radius.

- Solid angle unit

The steradian is the solid angle of a cone which, having its vertex in the centre of a sphere, cuts off on the surface of the sphere an area equal to that of a square with sides equal to the radius of the sphere.