As so often I am working on completing the ISO 639-3 coverage in OmegaWiki. This time I added fsl or French Sign Language. In the information on Ethnologue it says that it is taught in one school in Togo.
Given the information on Togo, it is the only sign language known. There are no other sign languages that have been recognised and, if this is the case, French Sign Language is certainly as good as any other. However, I can not help but wonder if there are no other sign languages. It seems odd to me that deaf people do not have their own sign language.
When there is a native sign language, it may be that because of the French Sign Language being taught at school this language is marginalised. When however the local language is strong, it may be that this French language is isolated ...
Really, languages are a really interesting subject. :)