### Standards

There are two standards for Scheme: an official standard with IEEE and a de facto one, often called “RnRS”, short for the Revisednth Report on the Algorithmic Language Scheme. In colloquial use, “Scheme standard” usually refers to the latter.

- The IEEE standard, 1178-1990 (R1995), should be available at technical bookstores, and from IEEE. I do not believe there are free on-line copies available. According to the document,

  > IEEE publications are available from the Institute of Electrical and Electronics Engineers, Service Center, 445 Hoes Lane, P.O.Box 1331, Piscataway, NJ 08833-1331, USA.

- You can find R7RS online, as well as R6RS. The Scheme Language Charter documents the process that led to the creation of R6RS. You can also find the older revisions, R5RS and R4RS, online.