Validity of unit area values and periodic revision thereof.

The unit area value of vacant land and the unit area value of covered space of building, as may be specified under section 103, in respect of a group in any ward shall remain in force for a period of five years and shall be revised at the expiration of each such period of five years: Provided that till the revision of such unit area values is completed, the existing unit area values shall continue to be in force.