Income Tax Demand & Limitation Act

I've receieved a letter from ITO stating that certain amount relating to AY 1993-94 has not been deposited & requested deposit of the same within 7 days. The assessment of AY 1993-94 was a scrutiny assessment & was subject to appeal that was decided in 1998.

a) Can ITO raise demand pertaing to AY 1993-94 in 2008?

b) Is the demand affected by limitation act?

Pls advise with relevant provisions & case laws