LANG: classes as instances

Would it be legal to have (in the same ontology) a statement 

  Individual( x, ...)

as well as a statement

  Class( x, ...)

If it is legal, what would it mean, e.g. can/should it refer to the same
'x'?
(I guess this falls under the SEM area) 

Guus

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A. Th. Schreiber, SWI, University of Amsterdam, Roetersstraat 15
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