The acronym OSD stands for Officer on Special Duty. It means the OSD officers are supposed to engage in a special kind of duty which ordinary officers cannot do. Special duty may be an assignment of project appraisal, or project preparation, giving special training to a group of officers, some kind of research work, pursuing higher degree abroad, etc. But the practical meaning of OSD in our government (excepting sending abroad) is to keep someone out of his job. In other words, it is a kind of silent punishment. The mechanism does not bring any good results, rather it creates acute frustration among the sufferers, sap their morale, humiliate them to the family and society as a whole. The money and the facilities spent for them is mere wastage.
It also damages his/her talent, experience and zeal for work. What are the reasons and ways to make a person OSD? These are not transparent. But the common ideas which are in vogue is that the officer/officers who are reported to be aid of the previous government and assumed to be their staunch supporters are normally disliked by the incumbent government. The members of the cabinet are not generally supposed to know these officers. But how are they identified? It is their colleagues or batch mates who report against them to the government high ups and based on these unproved, sometimes baseless reports, a good number of officers, who maintained a good track record and known as efficient, committed and spotless officers are made OSDs
The main reason for which an officer is normally made OSD is political not official.
So, OSDs (not charged with any genuine allegation) should be reemployed to the suitable posts very soon. Their performance and attitude may be watched and evaluated. There goes a proverb: an intelligent enemy is better than a foolish friend.