they are no similar one to another. There is a catalogue of sign languages. Some are standarised and some are in the process still. In Catalonia (Catyalunya) exist a sign language standarized since long time. This is not the important point,. The important point is that last year our "federal" parlament passed a law to introduce sign language as part of the curriculum of students since basic education. I mean students in the school who have not any problem with their abilities to speak or hear. I think here is the first place in the world this is done (if i m wrong, please tell me). Last week was a brief news in TV on this subject and it was really beautiful to see how both, kids with the inability and kids with the inability interacted and communicated among them.