Definition of case clarifies proceedings eligible for settlement before the Settlement Commission; scope of Bench, Chairman, Members, Interim Board. Section 245A defines 'case' for settlement purposes as any assessment proceeding pending before an Assessing Officer when an application under section 245C is made, and the Explanation specifies when various assessment, reassessment and fresh-assessment proceedings are deemed to have commenced or concluded; it also defines institutional terms including Bench, Chairman, Vice-Chairman, Member, Settlement Commission, Interim Board, income-tax authority, and the conditions which render an application a 'pending application'.