Appendix J of the ISO C standard (ISO/IEC 9899:2011 (E)) contains information about portability issues. Sub-clause J3 lists the behavior that each implementation must document. The following topics correspond to the relevant sections of sub-clause J3. They describe aspects of the Arm® C Compiler and C library, not defined by the ISO C standard, that are implementation-defined. Whenever the implementation-defined behavior of the Arm C compiler or the C library can be altered and tailored to the execution environment by reimplementing certain functions, that behavior is described as "depends on the environment".