Modelsim: Interpretation of numbers in wave window

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After a thorough investigation, this is simply a bug in Modelsim. Just replying for other users future knowledge.

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Though late but I think there is trivial misunderstanding of terminology.

It looks like Modelsim means by decimal as signed (without decimal point), unsigned as unsigned(without decimal point) and fixed point for binary with decimal point defintion. Thus your above

value is viewed without decimal point unless you choose fixed point. For signed/unsigned it ignores decimal point entered for fixed point.