To ease the resolving of Sudoku problems it is possible to mark candidates for fields. Just press the desired digit one up to nine in combination with the <Ctrl>-key. The program displays the candidate either using small digits or the Watch Hand Method according to the corresponding option. The pictures to the right shows a field with the candidates 1, 4, and 9 (the left one show candidates using digits, the right one using the "Watch Hand Method"). Certainly, these marks are printed out (however, if there is too little space to print digits, the candidates are printed out using the "Watch Hand Method"). To eliminate a candidate from a field, just press the candidate digit in combination with the <Ctrl>-key again.
The validity of candidates is not checked by the program, i.e., it is without any difficulty possible to enter a candidate in a field for which the program knows that this is totally senseless...
In addition to mark cells with candidates it is also possible to mark cells with "nagative candidates", i.e., values that cannot -- according to the users opinion -- be in that cell. To enter such a negative candidate press the <Shift>- and the <Ctrl>-key together with the negative candidate digit. To remove a negative candidate from a cell just press the respective key combination again.
Normal candidates are shown (or printed out) in green, negative ones in red.
Since the marking of candidates uses the same marks as the options "Show Possible Values" or "Print Possible Values" these options are switched off when entering a candidate.
To remove all candidates select the menu entry "Problem|Clear Candidates".