Parameter Collection MultiValue not implemented yet

The Parameter collection in Reporting Sevrices has a boolean property called MultiValue. I wanted to use this so we could tell the front end that the user should be able to return multiple values for this parameter. There is no where to set this value in the Report designer. So I added it to the RDL manually. But it always comes back false.

After searching the MS Reporting Service News Group  I found out this is not implemented yet. It is defined in the parameter class but not used. Even the help references it. MultiValue - Indicates whether the parameter can be a multi-value parameter. Boolean

Here is the response from MS in the news group:

The MultiValue element is part of the RDL specification published in 2003/10. It was not implemented in V1 of Reporting Services. It will be available in the next version. The MultiValue boolean flag determines if a report parameter is a multi value parameter.