In official IPA transcription, the click letter is combined with a via a tie bar, though is frequently omitted. Many authors instead use a superscript without the tie bar, again often neglecting the . This superscript is usually placed before the click letter, but may come after when the release of the velar or uvular occlusion is audible. A third convention is the click letter with diacritics for voicelessness, voicing and nasalization; it does not distinguish velar from uvular alveolar clicks. Common alveolar clicks are: