I know this may not directly merit any functionality provided by RDFIO but if time permits maybe consider the following re-factoring to ease maintenance in future by using some common assumptions about PHP.

• One class per file

  RDFIO/classes/RDFIO_ARC2StoreWrapper.php

  Lines 200 to 201 in 4338de2

  	class RDFIOARC2StoreWrapperException extends MWException {
  	}

• Remove dependency on MWException and use standard exceptions like RuntimeException or classes thereof
• Move classes (except for scripts) to /src and related sub-directories
  • When moving classes consider using the RDFIO namespace instead of naming each class with RDFIO...
  • Match class names against PSR-4 such as /src/Parser to correspond to RDFIO\Parser\ARC2ToWikiConverter.php
• For public functions use the public prefix to make visibility more clearer
• When moving a class try to create a simple unit test to at least cover the constructor (can be extended at any time)
• For "pure" unit tests avoid MediaWikiTestCase and instead use the standard PHPUnit_Framework_TestCase
• Documentation such as RDFIOCallGraph.pdf may find a more dedicated location (e.g. /docs)