كَسْرَة
A small slanting line ِ below a letter in Arabic, the sign of the vowel I. To indicate a long I it is followed by the consonant ya. In the indefinite genitive ending pronounced "in", the N is not written, but the kasrah is doubled ٍ.
In Unicode: plain kasrah is &1616; and doubled kasrah is ٍ. Here are examples with the consonant د d:
دِ di
دِى dii
دٍ din