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Multiracial people who wanted to acknowledge their full heritage won a victory of sorts in 1997, when the Office of Management and Budget (OMB) changed the federal regulation of racial categories to permit multiple responses. This resulted in a change to the 2000 United States Census, which allowed participants to select more than one of the six available categories, which were, in brief: "White," "Black or African American," "Asian," "American Indian or Alaskan Native," "Native Hawaiian or other Pacific Islander," and "Other." Further details are given in the article: Race (U.S. census). The OMB made its directive mandatory for all government forms by 2003.

When did the OMB change racial guidelines for the census form?
1997