Animal echolocation in the external ear. There are two hypotheses about the evolution of echolocation in bats. The first suggests that laryngeal echolocation evolved twice in Chiroptera, once in the Yangochiroptera and once in the horseshoe bats (Rhinolophidae). The second proposes that laryngeal echolocation had a single origin in Chiroptera, was subsequently lost in the family Pteropodidae (all megabats), and later evolved as a system of tongue-clicking in the genus "Rousettus". Individual bat species echolocate within specific frequency ranges that suit their environment and prey types. This has sometimes been used by researchers to identify bats flying in an area simply by
Do Not Track code of the Apache HTTP Server, which would make the server explicitly ignore any use of the Do Not Track header by users of Internet Explorer 10. Fielding asserted that Microsoft's decision "deliberately violates" the Do Not Track specification because it "does not protect anyone's privacy unless the recipients believe it was set by a real human being, with a real preference for privacy over personalization." The Do Not Track specification did not explicitly mandate that the use of Do Not Track actually be a choice until after the feature was implemented in Internet Explorer 10. Fielding pointed out that