The authorization behavior of blank invoice belongs to civil law behavior and there are differences between supplement authorization behavior and authorization behavior of agent rights of blank invoice. Based on above statement, the authorization behavior is defined as civil law behavior. 空白票据授权行为属于民事法律行为,而空白票据补充权的授权行为与代理权的授权行为有所差异,在此基础上将其界定为单方民事法律行为为宜。