Outputs the field f as a checkbox. The contents of the
first character of f is interpreted as the "status":
' ' = not selected
'X' = selected
The user can change this as required.
To prevent the user changing the contents of the checkbox, you can use the addition
... INPUT OFF. The checkbox is then nothing more than a status
display and can only be changed by programming.
In technical terms, a checkbox behaves exactly like
an input field with a length of 1 (FORMAT INPUT).
DATA: MARKFIELD(1) TYPE C VALUE 'X'.
...
WRITE MARKFIELD AS CHECKBOX.
"checkbox selected
MARKFIELD = SPACE.
WRITE MARKFIELD AS CHECKBOX. "deselected
WRITE MARKFIELD AS CHECKBOX INPUT OFF. "deselected, protected
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