The first system referred by Telles is that of the Brazilian Institute of Geography and Statistics (IBGE). In the Census, respondents may identify their ethnicity or color from five categories: "branca" (white), "parda" (brown), "preta" (black), "amarela" (yellow) or "indígena" (indigenous). The term "parda" needs further explanation; it has been systematically used since the Census of 1940. In that census, people were asked for their "colour or race"; if the answer was not "White", "preta" (black), or "Yellow", interviewers were instructed to fill the "colour or race" box with a slash. These slashes were later summed up in the category "pardo". In practice this means answers such as "pardo", "moreno", "mulato", "caboclo" etc., all indicating mixed race. In the following censuses, "pardo" was added as a category on its own, and included Amerindians. The latter were defined as a separate category only in 1991. It is a term for people of color who are lighter than blacks, and does not imply a black-white mixture, as there are some entirely indigenous persons.