To express vowels (singular, "sur"), Gurmukhī, as an abugida, makes use of obligatory diacritics called "lagā̃". Gurmukhī is similar to Brahmi scripts in that all consonants are followed by an inherent 'a' sound. This inherent vowel sound can be changed by using dependent vowel signs which attach to a bearing consonant. In some cases, dependent vowel signs cannot be used – at the beginning of a word or syllable for instance – and so an independent vowel character is used instead.