What this trainer is for
Roster preparation is one of the few establishment tasks where a single misplaced entry can be litigated years later. The rules are scattered across three decades of Office Memoranda and a line of Supreme Court judgments, and most people learn them by copying whatever the previous incumbent did. This is a place to practise on a roster that does not matter before you touch one that does.
The three exercises
- Prepare a roster. You are given a cadre strength and a mode of recruitment, and you assign each point to a category. Your work is marked point by point against the DoPT model roster, and every point you get wrong shows what it should have been.
- Operate it. Preparing the roster is the easy half. The questions that decide whether a roster survives scrutiny are about what happens next — an incumbent retires, someone is promoted out of the cadre, the sanctioned strength changes, only one vacancy arises in a year.
- Common errors. The mistakes that recur: recording an own-merit candidate against the reserved quota, adding a horizontally-reserved candidate to a vertical total, confusing shortfall with backlog, assuming a rule that applies to direct recruitment also applies to promotion.
Why the trainer does not calculate the roster
The Explanatory Note to the 1997 Office Memorandum gives the arithmetic: multiply each post by the percentage prescribed for a category, and the point at which the multiple reaches or oversteps a whole number is reserved for that category. In formula terms the n-th point of a category at percentage p falls at the smallest whole number P where P × p ≥ n.
That rule tells you the earliest point a category is entitled to, and it is worth understanding because it explains the shape of the roster. It does not, however, produce the published table. SC at 15 per cent is exactly double ST at 7.5 per cent, so every ST claim lands on a point an SC claim also wants, and the loser is displaced to the next free point. The order in which those collisions resolve does not follow one mechanical rule — checked against the published table, the raw formula accounts for 84 of the 119 reserved points and leaves 35 unexplained. There is also squeezing near the 100 and 200 boundaries, where displacement runs backwards so that each block of 100 contains exactly the whole-number quota.
So the published table is the answer key here, not a formula. If you see a roster generator online that claims to compute the points from percentages, check its output against the Office Memorandum before you trust it.
What the model roster actually contains
Over 200 points, for direct recruitment on an all-India basis by open competition: 30 SC, 15 ST, 54 OBC, 20 EWS and 81 unreserved — exactly 15, 7.5, 27 and 10 per cent. The first ST point is 14, the first SC point 7, the first OBC point 4 and the first EWS point 10, which is simply the arithmetic above applied to each percentage in turn.
A point about EWS worth correcting
A belief that circulates widely in establishment sections is that the introduction of EWS in 2019 pushed the SC, ST and OBC points around. It did not. Comparing the pre-2019 roster with the EWS-interpolated roster at Annexure-II to the 2019 Office Memorandum, all 200 SC, ST and OBC assignments are identical, and every one of the 20 EWS points was unreserved before 2019. EWS came entirely out of the unreserved pool, which fell from 101 points to 81.
Cadres of 13 posts or fewer
Where a cadre is too small for the percentages to produce a whole post — 7.5 per cent of 13 is under one, so ST would never be reached — a separate roster applies. It is read down the column to the cadre strength and then horizontally along that row for successive replacements, which is where the name L-shaped roster comes from. DoPT's own instrument covers cadre strengths up to 13 posts; the term "13-point roster" that entered common use during the 2018-19 teaching-posts controversy is about something different, namely whether the department or the institution is the unit of reservation.