The categorical variables COD_CONTRATO_DOCUM (type of rent) and
COD_TEMPO_MORADIA (rent time) have the occurrence of ZERO,
reading the data file, but that value doesn't have any categorical
meaning in any documentation from POF 2008-2009 survey (available for
download in the IBGE website). Because of that appears NAs in the
categorical variable when you read the data using the rotulos
parameter of the le.pesquisa function.