Expression Problem in FOSD

Kube of rank 2:

rows are structures (mandatory in yellow)
columns are operations (mandatory in yellow)

	Kore	Eval	ToString
Core	CK/Exp CK/Test	CE/Exp CE/Test	CP/Exp CP/Test
BaseNumber	BK/Num	BE/Num BE/Test	BP/Num BP/Test
Neg	NK/Exp	NE/Neg NE/Test	NP/Neg NP/Test
Plus	PK/Plus	PE/Plus PE/Test	PP/Plus PP/Test