String comparison oddities in 4GL

OK, so I've learned the hard way that string comparison works ... differently in Progress 4GL. For example, "x " and "x" seem to be the开发者_开发知识库 same thing, and "ß" is equal to "ss" - but "ö" is not equal to "oe".

Is there any comprehensive list of what substrings are considered equal in ABL? I've checked the documentation, but wasn't able to find any information on this behavior...

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OpenEdge Development: Internationalizing Applications. would probably be a good place to look. The "understanding code pages" chapter sounds like a likely jumping off point. I also find the COMPARE() function's documentation to be insightful with regards to how these things operate.