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Appendix B Standard Feature Identifiers

An implementation may provide any or all of the feature identifiers listed below for use by cond-expand and features, but must not provide a feature identifier if it does not provide the corresponding feature.

r7rs

All R⁷RS Scheme implementations have this feature.

exact-closed

The algebraic operations +, -, *, and expt where the second argument is a non-negative integer produce exact values given exact inputs.

exact-complex

Exact complex numbers are provided.

ieee-float

Inexact numbers are IEEE 754 binary floating point values.

full-unicode

All Unicode characters present in Unicode version 6.0 are supported as Scheme characters.

ratios

/ with exact arguments produces an exact result when the divisor is nonzero.

posix

This implementation is running on a POSIX system.

windows

This implementation is running on Windows.

unix, darwin, gnu-linux, bsd, freebsd, solaris, …

Operating system flags (perhaps more than one).

i386, x86-64, ppc, sparc, jvm, clr, llvm, …

CPU architecture flags.

ilp32, lp64, ilp64, …

C memory model flags.

big-endian, little-endian

Byte order flags.

⟨name⟩

The name of this implementation.

⟨name-version⟩

The name and version of this implementation.