A madd letter with no following cause for further prolongation takes madd asli—also called madd dhati or tabi‘i. Its traditional basic measure is one alif. It must not be clipped into a short vowel, nor prolonged arbitrarily beyond the ordinary measure.
«قَالَ» — basic length of alif.
«يَقُولُ» — basic length of waw.
«قِيلَ» — basic length of ya.
When a hamzah or a relevant sukun follows the madd letter, an additional condition can arise. This is the basis of secondary madd. The long vowel remains the same letter, but its extended duration is governed by the following cause and the selected recitational tradition.