Read this: The principles of phonological analysis can be applied independently of modality because they are designed to serve as general analytical tools, not language-specific ones. The same principles have been applied to the analysis of sign languages (see Phonemes in sign languages), even though the sub-lexical units are not instantiated as speech sounds.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): Instead of being language specific what kind of tool is sign language designed to be?
unanswerable