many variations of the rainbow flag have been used. some of the more common ones include the greek letter lambda (lower case) in white in the middle of the flag and a pink triangle or black triangle in the upper left corner. other colors have been added, such as a black stripe symbolizing those community members lost to aids. the rainbow colors have also often been used in gay alterations of national and regional flags, replacing for example the red and white stripes of the flag of the united states. in 2007, the pride family flag was unveiled at the houston, texas pride parade.