I'm converting a cursor to XML

CursorToXML('mytable','myoutput.xml') works fine the thing is when I try to convert it back with XMLtoCursor('myoutput.xml','mycursor') I get the error: "XML Parse error: Field width or decimal places is invalid"

The problem is that a character field in the original table contains only digits but is a 40 character field (example: "435553463785876868678", and when the XMLtoCursor tries to convert it back it assumes that is a numeric and overflows the numeric limits and generates an error.

Is there a way to specify to the cursortoxml function to state that thisfield is character en not numeric?

Thanks in advance