В custom code можно.
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Например:
В свойствах отчета в закладке Code
Public Function HasValue(ByVal parameter as Parameter, ByVal value as String) as Boolean
If parameter.IsMultiValue then
For i as integer = 0 to parameter.Count-1
if value = CStr(parameter.Value(i)) then
return true
end if
Next
End If
Return false
End Function

В отчете
=iif(Code.HasValue(Parameters!p1, "My Value"),"Yes","No")
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This posting is provided "AS IS" with no warranties, and confers no rights.