Section 8(4)(b) in The Indian Forest Service (Pay) Rules, 2016
(b)all his seniors in the cadre, except those regarded as unfit for such appointment, were serving in posts carrying pay in the said Level in which the benefit is to be allowed or in higher posts, and at least one junior was holding a cadre post, or an ex-cadre post within the permissible State Deputation Reserve or the over-utilized State Deputation Reserve permitted by the Central Government, under the Government of the State on the cadre of which he is borne, carrying pay in the said Level; and