Please Help: Buy back of own shares covered u/s 56(2)(viia) or not

Assessee a Company purchase / buyback its own shares at a price at which it was issued. The buyback price is lower than book value. Please let us know whether the difference between the book value and buyback price is taxable u/s 56(2)(viia). The company after buyback cancelled the said shares i.e. number of shares stands reduced. Further, some says that share is not covered in the definition of property. Please give your views as no direct case law is available on this.