* Visual Language: Sign languages rely on visual communication using handshapes, movements, and facial expressions. There's no concept of written letters, so uppercase and lowercase distinctions don't apply.
* Sign Variations: Different sign languages have different ways of representing letters, but these are usually just handshapes with a specific movement. For example, the sign for "A" might be a simple handshape, while the sign for "B" might involve a slight movement.
* Context is King: The meaning of a sign is determined by its context within a sentence or phrase. The way a sign is used within a sentence will determine its function and meaning, much like how punctuation and word order determine meaning in written languages.
So, while sign language might have different signs for specific letters, there's no concept of uppercase and lowercase.