Service classification: more specific service category determines tax applicability, preventing double taxation across overlapping services. Any service transaction is taxable only once and must be classified under the single service category that best fits the substance of the transaction; the more specific category prevails when categories overlap. A provider rendering multiple taxable services requires one registration endorsed for each taxable service and must discharge tax for each separately. The competent Central Excise officer must decide classification on merits; pending issues may be disposed of under these guidelines and past cases need not be reopened.