The field status specifies whether the field has been edited. It is
#f and when the user enters something and the data
buffer gets modified, it becomes
#t. So a field’s status can
be queried to find out if it has been modified or not.
The two procedures that work with field status are
field-status?. The procedure
field-status? returns the current state, and
set-field-status! can be used to set the state.