In SSIS SQL command What the ? means in set variable

Question

In SSIS package SQL command

DECLARE @UserName VARCHAR(32)
SET @UserName = ?

DECLARE @SecurityGroupID INT
SET @SecurityGroupID = ?

what does the ? means

Answer 1

? means parameter. In your case @UserName = @param1 and @SecurityGroupID = @param2.

You have to map the value of each parameter