BaseClassTraversion with Visual C++ 6.0 was probably not tested thouroughly by the developers of that compiler. Hence having both: base class and attribute traversion inside one function may generate an internal compiler error with VC++ 6.0.
When REFLIB_USE_RUNTIME_VBASE_FILTER is #defined the set of traversed virtual base classes will be calculated at runtime. In that case you can configure whether the filtering shall be recalculated on each traversion (better locality) or calculated once and stored as function static constant.

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