There is a "Language Changes" section beginning on page 77 of the PDF. R7RS-small should be considered mostly as building upon R5RS. Some potentially major ch

There is a "Language Changes" section beginning on page 77 of the PDF. R7RS-small should be considered mostly as building upon R5RS. Some potentially major changes include the introduction of a record system (user-defined types--basically structs), bytevectors, parameters (variables with dynamic scope), an enshrining of Unicode (implementations don't have to provide all of it--they can even be just ASCII--but what subset they provide must be Unicode-compatible), and a library system (you can define a library that "export"s a specific set of identifiers, and you can "import" identifiers from a library, optionally renaming individual ones or prefixing them all). There are also various fairly minor changes, such as giving "log" an optional second argument (being the base of the logarithm), requiring "write" to handle circular data structures, adding "when" and "unless" macros, and adding some utilities like "file-exists?", "delete-file", "get-environment-variable", and "command-line".