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The following two diagrams are nearly identical. However, in one, there are two ISA triangles from the Entity "Movie" and in the other there is just one.

What is the difference in meaning?

Two ISA Triangles

One ISA Triangle

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ISA in First diagram has no point. ISA is used as "either".

Movie CAN BE a Cartoon or Natural or movie MUST BE a cartoon or Natural.

There is no point to append an ISA while there is no either condition

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