Clicks are sometimes said to be doubly articulated, as they involve a coronal (more rarely labial) forward articulation, which defines the various 'types' of clicks and the IPA letter assigned to them, plus a dorsal closure. However, this second, dorsal place of closure functions as part of the controlling mechanism of the lingual ingressive airstream used to generate the click. Thus, much as the glottal closure of ejectives (the airstream-generating mechanism of such consonants) is not considered to be a second place of articulation, clicks are not generally described as such either. Indeed, it is possible to have a true doubly articulated click, such as the labial-dental allophone, , of the bilabial click in Taa.