First thing's first: This system is not meant to co-opt deaf culture in any way, nor is it a replacement for American Sign Language. It’s an alternative for a Dominant who needs to communicate their wishes to a submissive when verbal commands may be difficult to hear. I've found there's a surprising number of situations when non-verbal commands come in handy. The most common is in dungeons or at kink parties, where loud music or noise is a problem. They can also be useful when the submissive is hard of hearing or has earplugs in.
This is an alternate system of communication I initially developed with my subs during play in loud public play spaces. I'm old, enjoy high protocol D/s, and can't hear well. I also love using sensory deprivation, like earplugs and headphones, on my submissives. In addition to being practical in loud environments, this system also enforces the discipline I instill in my submissives through memorization, service and structure. It’s perfect for those into service oriented protocol because it is so regimented. Lastly, it offers a fair system for developing punishments for a sub who can’t recall one of the commands. You can use it in quiet environments too just to keep your submissive on their toes.