special procedure under Sections 245C and 245D in Chapter XIX-A shows that special type of computation of total income is engrafted in the said provisions which is nothing but assessment which takes place at Section 245D(1) stage . However, in that computation, provisions dealing with regular assessment, self-assessment and levy and computation of interest for default in payment of advance tax, etc. are engrafted. Sections 234A, 234B and 234C are applicable to proceedings of Settlement Commission under Chapter XIX-A of Act to above extent.