BTR is really easy for some charts.(In those charts where the error in noting down timings in minimal. In these days its easier to note a near corrrect Birth time at Birth time, unlike those olden days, when they used to say, Us din shaam ko paida hua tha, mandir ki ghanti baji thi tab etc.etc. so the margin of errors is just a few minutes on either side) What factor changes in the Horoscope Statistics during few minutes of birth time going awry ? Nakshatra of Lagna will remain same for a longer period, but Only SubLord will show changes for a shorter period.In BTR we normally use the LSRD or the RP's to rectify the Birth time,.RP's means the Ruling Planets at the moment of judgement when the Astrologer sits to judge the birth time.LSRD simply means as under-L for Lagna Lord at moment of Judgement.S for Moon Star at moment of Judgement.R for Moon Raashi at moment of Judgement.D for Day lord at moment of Judgement.Lagna Star Lord is also utilised additionally if required. (I use this only when have no recourse from LSRD).The method which my Late Guruji Shri Suresh Sahasne taught me is as under -(I am writing in short and specific to the point with no Bhoomika or unnecessary introductions to any Topic).1) The 4 Planets which represent the LSRD at moment of judgement must be noted down.2) Cast a chart as per recorded Birth time and check who is the SubLord of the ascendant.3) If the SubLord of the ascendant is also one of the Planets in the LSRD, then it means that the Birth time is accurateand needs no rectification.4) If the SubLord does not match any of the Planets in the LSRD, then adjust the recorded Birth timings either a little beforeor after , so as to match the first component in the LSRD which is easily available.Now our Example-Place of Judgement - Bombay,Date 25th July 2011, Time of judgement IST 11.55.28 Now what are the Ruling Planets (RP's) at time of Judgement ?Lagna was Virgo - So Lagna Lord MercuryMoon Star was Krittika - So Moon Star Lord the Sun.Moon Raashi was Taurus - So Moon Raashi Lord VenusDay is Monday - So Day lord is the MoonTherefore LSRD is Mercury, Venus, The Sun, and the Moon.Recorded Birth time - 23.45.00 IST on 2nd July 1990 at HyderabadOn Casting Chart (KP Ayanamsha) we get ascendant Pisces with Saturn as Nakshatra Lord and Venus as SubLord.Now the Sub Lord Venus is present in our LSRD , which means that the Birth time is correct and needs no rectifications apparently.But theres a catch here in this example. In the RP's theres one more rule, that if Raho or Ketu are present in any raashis the Lord of which is present in the RP's, then the Node will gain more importance than the Planet. At the time of taking RP's Ketu was in raashi of Venus (Taurus), therefore Ketu will replace venus, as the Nodes are considered stronger in KP rather than planets.So we need rectifications. We need to bring the SubLord arrived at by casting the chart at recorded birth time to include one of the planets in the LSRD.Now Ketu is the planet which comes before Venus in the Vimsottari dasha order, and the Sun is the planet which comes in later. So which one to pick as both are present in the LSRD . I will choose the previous one which is Ketu. Why ? Because Mercury, Venus and Moon suggest fast moving planets which means that the Birth could have been earlier. (Had Saturn been present in the LSRD I may have possibly opted for the Sun to make my choice as the SubLord).So okay I make my choice. The equation for the new rectified Birth time must have Jupiter as Lagna Lord, Saturn as Nakshatra Lord, and ketu as SubLord. But I am still not happy, because certain perfection minded people have troubled me a lot in last few days with their "seconds" theory. And want to be more perfect. So I will now choose a SubSub lord. Among the many available I will go for Mercury because it Heads the LSRD and that order is actually Listed in importance ,when making choices. I choose Mercury as the SubSub Lord.Now to arrive to Mercury as Sub SubLord I need to adjust the Birth timings accordingly.I arrive at rectified Birth time of IST 23.39.10 in order to have the SubLord as Ketu and SubSubLord as Mercury. Now for those who may want to know the extent of the SubLord and SubSubLord divisions they need to have the Table with them to make fast calculations within minutes. The Traditional Astrologers already know that the area Pisces 03.20 degrees uptil 16.40 is goverened by U.Bhadra owned by Saturn, which is why we did not have to bother trying to change the Nakshatra Lord. Since the child had it been born 18 minutes earlier or 24 minutes later than the recorded time, the Querent would have told us so....You may ask me n number of questions on above Case to confirm whatever is not understood here