Viseme/Phoneme Explaination

Is there any sort of documentation explaining what the 12 visemes are, or if they map to any standardized set of phonemes (IPA/CMU)?

Something like this Azure Viseme Documentation - https://github.com/MicrosoftDocs/azure-docs/blob/main/articles/ai-services/speech-service/how-to-speech-synthesis-viseme.md#map-phonemes-to-visemes