Are you talking about International Sign Language which we could learn and understand which we can traveled any place in the world to visit as tourists? International Sign Language is universal.
Some countries use their own sign language while other countries adopt BSL like Australia. And other countries adopt ASL like South America.
I agree with Hoichi that there is a difference on the letter of d and D. Deaf is cultural and being Deaf is a gift while the small letter for d for deaf is a medical terminology and is a curse by the hearing people, not us.
