Doke had run "admirable" experiments establishing the nature of click consonants.
Summarized below is the evolution of formal click transcription, from Bleek's digraphs reflecting co-articulated consonants, to ligatures intended to function as single letters, to full IPA with diacritics, along with an equivalent treatment of the tenuis, voiced, and nasal non-click occlusives (for illustrative purposes) [REF].||} .