This class specifies data for a particular data point. It is used for both numCache and numLit object
creates a new NumVal object
Creates the val objects for this data set. I am not overly confident this is going to play nicely with time and data types.
A string representing the format code to apply. For more information see see the SpreadsheetML numFmt element's (§18.8.30) formatCode attribute.
serialize the object