美国邮票的暂定编号系统

基于世界邮票目录/编号系统，以下编号系统正在尝试用于美国邮票

Format:  CCC - YYYY - SSDD - TTKK
         ---   ----   ----   ----
Example: USA - 1851 - 0101 - 3201
         ---   ----   ----   ----
where: CCC  = 3-letter country code
                (USA = United States)
       YYYY = 4-digit year of issue
                (1851 = Year of issue)
       SS   = 2-digit series order (varies by year)
                (01 = first (and only) series for 1851)
       DD   = 2-digit denomination order (varies by series)
                (01 = 1-cent, 02 = 3-cent, 03 = 5-cent, etc.)
       TT   = 2-digit type and subtype (varies by denomination),   
                (31 = Type III, 32 = Type IIIa)
       KK   = 2-digit color variation (varies by denomination),
                (01 = first (and only) color for this denomination (blue))

随着更多邮票被编入目录，这个编号系统可能会发生一些变化。这个系统可能不适用于在美国发行的当地、邮政局和临时邮票。哈哈！