Intel® Fortran Compiler 17.0 Developer Guide and Reference
This section presents topics to help you understand how language standards, operating system differences, and computing hardware influence your use of Intel® Fortran and the portability of your programs.
Your program is portable if you can implement it on one hardware-software platform and then move it to additional systems with minimum changes to the source code. Correct results on the first system should be correct on the additional systems. The number of changes you might have to make when moving your program varies significantly. You might have no changes at all (strictly portable), or enough that it is more efficient to design or implement a new program (non-portable customization). Most programs in their lifetime will need to be ported from one system to another, and this section can help you write code that makes this easy.