Where is the confusion in working out modalities? May be the Hon'ble RM and the Hon'ble MoS for I & B have not been privy to the Services HQ DGL (worked out based on 5 years data provided by AFCAO).
Here it is quoted verbatim
"Modalities of OROP
5. Till now, Qualifying Service (QS) was rounded off to nearest six months. QS was reckoned for calculation of pensions and was linked to 33 years of service for full pension. In the revised pay structure, annual increment is admissible to all personnel on 01 July of each year and linkage of 33 years for full pension has also been done away with. Therefore, there is no need now to have QS for six monthly periods. Instead, it will be calculated by rounding off the length of service to the nearest completed year for each pensioner. However, the minimum actual service required for eligibility of pension will remain unchanged.
6. The best pay scale of the group for each rank across the three services was accepted for the purpose of revision of pensions in respect of pre 2006 pensioners. It was determined based on the notional maximum for the ranks across the three Services. In case of officers the pension was fixed with respect to the minimum of pay in the fitment table as given in SAI/SNI/SAFI 2/S/2008. The modified parity in pension based on the best pay scale across the services was promulgated vide Govt of India, Ministry of Defence, letter No 1(13)/2012/D (Pen/Policy) dated 17.01.2013.
7. In view of the above, notional pension based on the highest pay, as on 01 July, actually drawn by each rank with reference to the length of QS is extended to all past pensioners. The annual increments are now admissible only on 01 July each year. Therefore, the highest pay for the rank and length of service drawn on 01 July, after taking into account the annual increment admissible on that day, will be reckoned for notional pension under OROP.
(a) In order to implement OROP, the initial upgradation of pension will be made with effect from 01 Apr 2014 and thereafter on 01 July every year starting 01 July 2014 (after taking into account the annual increment). This will ensure automatic enhancement of rates of pension for past pensions based on the future enhancements in pensions.
(n) The pension of current pensioners for all time bound ranks (i.e. up to the rank of Col and equivalent) will be extended to past pensioners with the same length of commissioned service applicable to each rank, if the past pensioners had retired before 16 Dec 2004 before the time period for promotions was reduced. For this purpose the years of service will only be relevant and the table for the higher rank shall be taken into consideration to determine the pension of such retirees. In all cases of future changes in the time period for any time bound rank/pay scale, the OROP pension shall include this benefit for all past pensioners only if they become eligible for promotion had they still been in service.
10. Since OROP extends the pension of current pensioners to all past pensioners, any changes in policy regarding pay or promotion which affect the pay/pension of future pensioners, shall also be passed on to the past pensioners from the same date."