How do I define the schema so I can set the elements value to nothing?

[Pa...@wellsfargo.com]

Using Apache AXIS 1.2 and have an operation that updates a database. The
elements in the request message are of a number of types: xs:boolean,
xs:date, xs:string (many of which are enumerations). Have the
requirement to "clear out", or "erase", or "set to null or nothing"
these elements after they've already been set. The business example
would be if a 'deceased date' was accidentally entered into the database
and when the mistake was discovered how would the consumer of the web
service send the request to clear out the value?