* SCM Standards Conformance

• IEEE Standard 1178-1990,
  IEEE Standard for the Scheme Programming Language,
  ISBN 1-55937-125-0.

• William Clinger and Jonathan Rees, editors.
  Revised⁴ Report on the Algorithmic Language Scheme
  ACM Lisp Pointers 4(3), pages 1-55, 1991.

• Richard Kelsey and William Clinger and Jonathan Rees (Editors),
  Revised⁵ Report on the Algorithmic Language Scheme
  ACM SIGPLAN Notices 33(9), pages 26-76, 1998.

When compiled with floating-point number support, SCM's numerics are instead described mostly by:

• Aubrey Jaffer,
  SRFI 70: Numbers,
  http://srfi.schemers.org/srfi-70/

• Aubrey Jaffer,
  SRFI 94: Type-Restricted Numerical Functions,
  http://srfi.schemers.org/srfi-94/

• There are no exact (complex) non-real numbers (the only exact numbers are integers).
• The procedures gcd, lcm, modulo, remainder, quotient, even?, and odd? accept only exact integer arguments.
• Division by zero returns an infinity instead of erring.
• (/ 0 0) returns a NaN instead of erring.
• (log 0) returns an infinity instead of erring.
• (expt 0 -1) returns an infinity instead of erring.
• (* 0 (expt 0 -1)) returns a NaN instead of erring.
• The procedures number->string and string->number do not always meet the inversion constraint "using the minimum number of digits". I hope to see this get corrected. When SCM is compiled by an optimizer (like gcc -O2) which generates code which uses 80.bit intermediate floating-point values, violations of the inversion constraint are rare in practice.