ProcessID_Filter is a read-only property of the IMessageFilterNames interface that returns the filter name expected by the List2 method for filtering by the process ID of the application that logged a message.
The process ID of the running application is automatically obtained and added to messages posted with MessageLog2.SendLogMessage.
The object placeholder is an object expression that evaluates to a IMessageFilterNames interface.
The IMessageFilterNames interface can be obtained directly from the MessageLog2.MessageFilterNames property or by using QueryInterface (assignment, in VB, casting in .Net) on a MessageLog or MessageLog2 object.
When adding to the NamedValues collection, the IMessageFilterNames interface acts with Intellisense to show the available parameter options and ensures only names that are supported are used.