Services
(1) Parliament may vary/revoke (even retrospectively) the service conditions of certain pre-independence "Secretary of State" civil service appointees who continued serving after independence - though it cannot worsen the service conditions, after their appointment, of anyone who became Chief Justice/Judge, CAG, a Public Service Commission Chairman/member, or Chief Election Commissioner, except regarding conditions applicable to them purely as a legacy Crown appointee. (2)-(4) This doesn't otherwise limit normal service-condition regulation powers, courts have no jurisdiction over certain related legacy disputes, and this article overrides the original Article 314 and any other conflicting provision.
This is a narrow, largely historical provision (added by the 28th Amendment, 1972) dealing specifically with civil servants who were originally appointed under British colonial authority before 1950 but continued serving India after independence - letting Parliament adjust their legacy service terms, while specifically protecting certain high constitutional office-holders from having their terms worsened after appointment.
This provision is now of largely historical interest, since it dealt with a category of civil servants (those originally appointed by British colonial authority) who have long since retired or passed away.