Using Date Modifiers in file masks are a great way to increase the speed of your imports as they remove all the logs you don’t care about from the import list. If you're using WebSpy Vantage, you are probably interested in filtering your log file imports by date (only import files from the month of June for example). The obvious way to do this is to specify a date filter using the filters page in the Input Wizard. The problem is Vantage will still check every record in every log file being imported to see if it matches the date filter. If you have months or years worth of logs in the folder being imported, that's a lot of data that Vantage has to pointlessly sift through. The good news is, if your log files contain the date in their file name, then you can use file masks to instruct Vantage to never touch these unwanted files.