abap_bool的几种定义

1：

types:
  abap_bool type c length 1.
* constants for abap_bool
constants:
  abap_true      type abap_bool value 'X',
  abap_false     type abap_bool value ' ',
  abap_undefined type abap_bool value '-',
  abap_on        type abap_bool value 'X',
  abap_off       type abap_bool value ' '.