Hi All, I'd like to add derived property in a column. but I don't know which keyword is used or how to add it in xsd.

my problem is eg., in a UML class, there are three attributes -

lowSize : Integer,
highSize : Integer
/avgSize : Integer

this last attribute /avgSize has a derived value : { AvgSize = (LowSize + HighSize)/2 }. I added this value in datacolumn.default of datatable.but can't. because /avgSize attribute's data type is Integer. my default value is a string ' (LowSize + HighSize)/2 '. so i got this error.

pls help me. i will show it to my teacher on this coming Monday.