Provisions stipulated under the CCS (Leave) Rules, 1972 regulating Extra Ordinary Leave to central Govt. employees are explained here under.

1.         Extra-ordinary Leave to Permanent Employee [CCS Leave Rule – 32(1)]
Extraordinary leave (subject to maximum limit as per Rule-12, i.e. 5 years) may be granted to a Government servant (other than a military officer) in special circumstances-
(a)        When no other leave is admissible.
(b)        When other leave is admissible, but the Government servant applies in writing for the grant of extraordinary leave.

2.         Extra-ordinary Leave to Temporary Employee [CCS Leave Rule – 32(2)]
Unless the President, in view of the exceptional circumstances of the case otherwise determines, no Government servant, who is not in permanent employ or quasi-permanent employ, shall be granted extraordinary leave on any one occasion in excess of the following limits:-
(a)        Three months;
(b)        Six months where the Government servant has completed one year’s continuous service on the date of expiry of leave of the kind due and admissible under these rules, including three months’ extraordinary leave under Clause (a) and his request for such leave is supported by a medical certificate as required by these rules;
(c)        Eighteen months, where the Government servant who has completed one year’s continuous service is undergoing treatment for – (i) Pulmonary Tuberculosis or Pleurisy of tubercular origin, in a recognized sanatorium; (ii) Tuberculosis of any other part of the body by a qualified Tuberculosis Specialist or a Civil Surgeon or Staff Surgeon; or (iii) Leprosy in a recognized leprosy institution or by a Civil Surgeon or Staff Surgeon or a Specialist in leprosy hospital recognized as such by the State Administrative Medical Officer concerned; (iv) Cancer or for mental illness, in an institution recognized for the treatment of such disease.
(d)        Twenty-four months, where the leave is required for the purpose of prosecuting studies certified to be in the public interest, provided the Government servant concerned has completed three years’ continuous service on the date of expiry of leave of the kind due and admissible under these rules, including three months’ extraordinary leave under Clause (a).

3.         Requirement of Bond [CCS Leave Rule – 32(3)]
(a) Where a temporary Government servant is granted extraordinary leave for the purpose of prosecuting studies, shall be required to execute a Bond in Form 6 undertaking to refund to the Government the actual amount of expenditure incurred by the Government during such leave plus that incurred by any other agency with interest thereon in the event of his not returning to duty on the expiry of such leave or quitting the service before a period of three years after return to duty.
(b) The Bond shall be supported by Sureties from two permanent Government servants having a status comparable to or higher than that of the Government servant.

4.         EOL to SC/ST Employees [CCS Leave Rule – 32(4)]
Government servants belonging to the Scheduled Castes or the Scheduled tribes may, for the purpose of attending the Pre-Examination Training Course at the centers notified by the Government from time to time, be granted extraordinary leave by Head of Department in relaxation of the provisions of sub-rule (2).

CCS Leave Rule – 32(5) – Two spells of extraordinary leave, if intervened by any other kind of leave, shall be treated as one continuous spell of extraordinary leave for the purposes of sub-rule (2).

CCS Leave Rule – 32(6) – The authority competent to grant leave may commute retrospectively periods of absence without leave into extraordinary leave.