Page "Porting" Paragraph 6

International standards, such as those promulgated by the ISO, greatly facilitate porting by specifying details of the computing environment in a way that helps reduce differences between different standards-conforming platforms.

Writing software that stays within the bounds specified by these standards represents a practical although nontrivial effort.

Porting such a program between two standards-compliant platforms ( such as POSIX. 1 ) can be just a matter of loading the source code and recompiling it on the new platform.

However, practitioners often find that various minor corrections are required, due to subtle platform differences.

Most standards suffer from " gray areas " where differences in interpretation of standards lead to small variations from platform to platform.