What is 'Source Code'?
Source code - A computer program written by a programmer in a source language. Source code is input to a compiler or assembler, in order to derive object code (machine code).
In the case of Xoops the source code is not compiled and remains open for viewing and change.
This Q&A was found on XOOPS Web Application System : https://xoops.org/modules/smartfaq/faq.php?faqid=228