As the public sign is a kind of text with such vocative functions as directing, reminding, warning, noticing, persuading and publicizing, it falls into the type of vocative texts.

• 公示语是一种具有指示、提示、警示、告示、劝导和宣传等感召功能的文本,根据纽马克的文本类型理论,应当属于感召型文本。