Concessional excise exemptions may be availed concurrently, subject to each notification's conditions and aggregate clearance rules. Notification No. 75/87-C.E. grants concessional excise treatment for refrigeration and air conditioning goods with specified exempt slabs and aggregate-value limits, excluding certain wholly exempt clearances from aggregation. The circular clarifies that Notification No. 75/87-C.E. does not preclude simultaneous use of Notification No. 175/86-C.E.; both benefits may be availed together if respective conditions are observed, but clearances under the two notifications must be clubbed for computing aggregate clearances.