Thank you, Stefan, for your extensive clarifications. Your approach might be the correct way to deal with this kind of stuff when programming in plain Tcl, and maybe as well in special cases when implementing NaviServer/OpenACS applications. However, in the typical case of development "inside the framework (NaviServer/OpenACS/XO* Packages)", there is usually no need to convert values from or to UTF-8. The framework deals already with this, so most attempts to "convert" something result in over-converting something.
Actually, the developer who faced this bug in the first place, tried to fix the problem using "convert", and even thought she had fixed it (using [encoding convertfrom [ns_conn encoding] $result]). However, this "fixed" the problem only for German umlauts, not for the three-byte sun (which was not part of the initially observed problem).
During code review I saw this "conversion-based fix" and immediately had the suspicion that there must be something wrong at some other place. Now that we have found the bug, or at least a solution within the framework, everything is fine! Thank you!
