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Unfortunately, "index.php?mact=Calendar" is not a folder, it's a page+parameter. If you tried to block that as a folder in GWT, it would mostly just not work. If it went really wrong, you'd block anything driven from index.php (including your home-page). A couple of options: (1) Programmatically META NOINDEX anything that calls the calendar parameters. This would have to be done selectively in the index.php header with code, so that ONLY the calendar pages were affected. (2) Block "mact=" or "year=" with parameter handling in GWT. under "Configuration" > "URL Parameters". ONLY do this if these parameters drive the calendar and no other pages. You can basically tell Google to ignore pages with "year=" in them. You can also block parameters in Robots.txt, but honestly, once the pages have been indexed, it doesn't work very well.