Consonant letters are classified in three series, based on vowel harmony: soft, hard, and neutral. The soft consonant letters, ت س ك گ ه, are found in front vowel (e, i, ö, ü) contexts; the hard, ح خ ص ض ط ظ ع غ ق, in back vowel (a, ı, o, u) contexts; and the neutral, ب پ ث ج چ د ذ ر ز ژ ش ف ل م ن, in either. In Perso-Arabic borrowings, the vowel used in Turkish depends on the softness of the consonant. Thus, "klb" 'dog' (Arabic /kalb/) is /kelb/, while "ḳlb" 'heart' (Arabic /qalb/) is /kalb/. Conversely, in Turkish words, the choice of consonant reflects the native vowel.