What is the eligibility and term limit for a Vigilance Commissioner to be appointed as the Central Vigilance Commissioner according to the Central Vigilance Commission Act, 2003?

Section 5. Terms and other conditions of service of Central Vigilance Commissioner: (2) Subject to the provisions of sub-sections (3) and (4), every Vigilance Commissioner shall hold office for a term of four years from the date on which he enters upon his office or till he attains the age of sixty-five years, whichever is earlier: Provided that every Vigilance Commissioner, on ceasing to hold the office, shall be eligible for appointment as the Central Vigilance Commissioner in the manner specified in sub-section (1) of section 4: Provided further that the term of the Vigilance Commissioner, if appointed as the Central Vigilance Commissioner, shall not be more than four years in aggregate as the Vigilance Commissioner and the Central Vigilance Commissioner.