IDSM meaning in General ?

The Indian Distinguished Service Medal (IDSM) was a military decoration awarded by the British Empire to Indian citizens serving in the Indian armed forces and police. When it was instituted in 1907 it was the second highest award available to Indians, behind the Indian Order of Merit, however, when eligibility for the Victoria Cross was extended to cover all Commonwealth subjects in 1911, the IDSM became third highest in the order of precedence. It was instituted in order to recognise acts of gallantry that did not meet the standards required of the IOM. Following the Partition and subsequent independence of India in 1947, it was decided to discontinue the award.

Upon being instituted the medal was only available to members of the British Indian Army, Indian State Forces, militias and levies, however, after 1917 it was extended to 'non-combatant' followers, such as carriers and grooms. In 1929, eligibility was extended to the Royal Indian Marine and to the Indian Air Force in 1940.

There were four versions of the medal, the only difference being the monarch depicted on the obverse. The medals were issued either with the engraved or impressed details of the recipient, including service number, name and regiment.

The medal is considered reasonably rare and only about 6,000 were awarded, including bars. About 3,200 were awarded during the First World War, and 1,200 from the start of the Second World War to 1947. The remaining 1,600 were awarded between the wars during frontier fighting and other inter-war campaigns such as the Iraq campaign of 1919–20.