International Sign Definition

International Sign (IS) is a contact variety of sign language used in a variety of different contexts, particularly at international meetings such as the World Federation of the Deaf (WFD) congress, events such as the Deaflympics, in video clips produced by Deaf people and watched by other Deaf people from around the world, and informally when travelling and socialising. It can be seen as a pidgin form of sign language, which is not as conventionalised or complex as natural sign languages and has a limited lexicon.

Dr. Robert Adam, WFD Sign Language Expert, April 2014.
http://en.wikipedia.org/wiki/International_Sign
examples: https://www.youtube.com/user/TheWASLimedia