in may 2011, microsoft filed patents for an optically see-through eyewear display with augmented reality capabilities. the patent describes how it could augment the wearer's view by using the device. for instance, it could be used at a baseball game to show a player's statistics, provide details of characters in a play, or at an opera house to show the lyrics next to the opera singer as an alternative to displays placed at the side of the stage. it also states that the eyewear display could be operated by a wrist-worn computer, voice-commands or by flicking the eyes to a certain spot. in 2012, a two-year-old 56-page roadmap document by microsoft appeared on scribd. it revealed that microsoft's innovation center in fortaleza, brazil is developing the code-named fortaleza, an eyewear display that appears to be wi-fi and 4g-enabled and incorporates augmented reality. it also revealed plans to make it capable of syncing with microsoft's xbox one and the kinect. no concrete release date was given, but the document suggests sometime in 2014 at earliest. the document was removed at the request of covington & burling llp, an international law firm that represents microsoft. the file has since found a home on multiple hosting services and websites, but soon afterwards microsoft sent takedown notices to sites that were hosting the document, including dropbox. ihned.cz, a technology site based in the czech republic, received a notice from alan radford, internet investigator on behalf of microsoft for hosting the document. in 2014, microsoft revealed the device, naming it hololens. in an 6 october 2015 event microsoft demonstrated the demo of hololens and made its developer edition available at $3000.