"Solar" and "lunar" became descriptions for these instances as the words for "the moon" and "the sun" (al-qamar and ash-shams, respectively) are examples of this rule. Emission points There are 17 emission points (makhārij al-ḥurūf) of the letters, located in various regions of the throat, tongue, lips, nose, and the mouth as a whole for the prolonged (madd or mudd) letters. The manner of articulation (ṣifat al-ḥurūf) refers to the different attributes of the letters. Some of the characteristics have opposites, while some are individual. An example of a characteristic would be the fricative consonant sound called ṣafīr, which is an attribute of air escaping from a tube. Thickness and thinness The emphatic consonants , known as letters, are pronounced with a "heavy accent" (). This is done by either pharyngealization /ˤ/, i.e. pronounced while squeezing one's voicebox, or by velarization /ˠ/. The remaining letters – the muraqqaq – have a "light accent" (tarqīq) as they are pronounced normally, without pharyngealization (except , which is often considered a pharyngeal sound). () is heavy when accompanied by a or and light when accompanied by a kasrah. If its vowel sound is cancelled, such as by a or the end of a sentence, then it is light when the first preceding voweled letter (without a sukun) has a kasrah. It is heavy if the first preceding voweled letter is accompanied by a fatḥah or ḍammah. For example, the at the end of the first word of the Sūrat "al-ʻAṣr" is heavy because the () has a fatḥah: () is only heavy in the word . If, however, the preceding vowel is a kasrah, then the in is light, such as in the Bismillah: Prolongation Prolongation refers to the number of morae (beats of time) that are pronounced when a voweled letter (, , ) is followed by a madd letter (alif, yāʼ or wāw). The number of morae then becomes two. If these are at the end of the sentence, such as in all the verses in "al-Fatiha", then the number of morae can be more than two, but must be consistent from verse to verse. Additionally, if there is a maddah sign over the madd letter, it is held for four or five morae when followed by a () and six morae when followed by a . For example, the end of the last verse in "al-Fatiha" has a six-mora maddah