Question on exon skipping/casette exon

[sparthib]

Does exon skipping correspond to the subcategory "combination of known splice sites" under NIC?

EDIT: Follow up question, how is this subcategory different from "combination of known splice junctions?" As far as I can tell from the schematic, it's when the novel transcript has a combination of splice junctions from multiple reference isoforms. Whereas for the "known splice sites combination", it's splice sites from a single reference isoform. Is this interpretation right?

A more general question: How does SQANTI3 define a "splice junction" vs. a "splice site"?

Thanks,

Sowmya