下列常量由此扩展定义,且仅在此扩展编译入 PHP 或在运行时动态载入时可用。
CAL_GREGORIAN
    (integer)
   CAL_JULIAN
    (integer)
   CAL_JEWISH
    (integer)
   CAL_FRENCH
    (integer)
   CAL_NUM_CALS
    (integer)
   CAL_DOW_DAYNO
    (integer)
   CAL_DOW_SHORT
    (integer)
   CAL_DOW_LONG
    (integer)
   CAL_MONTH_GREGORIAN_SHORT
    (integer)
   CAL_MONTH_GREGORIAN_LONG
    (integer)
   CAL_MONTH_JULIAN_SHORT
    (integer)
   CAL_MONTH_JULIAN_LONG
    (integer)
   CAL_MONTH_JEWISH
    (integer)
   CAL_MONTH_FRENCH
    (integer)
   以下常量自 PHP 4.3.0 起可用:
CAL_EASTER_DEFAULT
    (integer)
   CAL_EASTER_ROMAN
    (integer)
   CAL_EASTER_ALWAYS_GREGORIAN
    (integer)
   CAL_EASTER_ALWAYS_JULIAN
    (integer)
   以下常量自 PHP 5.0.0 起可用:
CAL_JEWISH_ADD_ALAFIM_GERESH
     (integer)
   CAL_JEWISH_ADD_ALAFIM
     (integer)
   CAL_JEWISH_ADD_GERESHAYIM
     (integer)