This is help for verson 0.1 of SPT, the Sudoku Puzzle Tool from ECSI. 
                               
General Information
-------------------

SPT is intended to help solve the 9x9 Sudoku puzzles that appear in the
daily newspapers. An edit mode is provided for manual entry of puzzles, and
facilities are provided to store and load puzzles to/from disk files.

With the current version of SPT, the method of interactive puzzle solution
is as follows:
  
    1) The program calculates and displays all the candidates for all
       the unresolved positions in the puzzle, based the contents of the
       positions that have already been resolved (either by having been
       specified in the original puzzle, or because of earlier operation
       action); and
       
    2) The operator solves the puzzle by considering resolved positions
       along with the candidates for the unresolved positions, and one 
       by one and either:
       
           a) "Promotes" candidates to resolved status by placing the
              cursor over them and hitting the ENTER key; or
             
           b) "Excludes" candidates by placing the cursor over them and
               hitting the DELETE key.
       
       After each operator action, the program recomputes the candidate
       data and re-displays the current state of the puzzle; when all
       positions have been resolved, the solution is complete. 

The current version of SPT _does not_ prevent operator errors in the course
of the promotion / exclusion process, so it is entirely possible that manual
solution bogs down in an impossible situation (such as _no_ candidates for
one or more positions). An Undo/Redo facility is provided to deal with this
possibility.
 
Program Modes
-------------

SPT has two operating modes: Solution Mode, which supports the candidate
promotion / exclusion process; and Edit Mode, which allows the operator to
key in puzzles and store/load puzzles to/from disk. Function key F10 is
used to switch between these modes.

Edit Mode
---------

Edit Mode provides for interactive entry of puzzles and also for loading and
storing puzzles from/to disk files. A built-in sample puzzle can also be
loaded in Edit Mode; once loaded, the sample puzzle can be stored to a disk
file under a user selected name in order to create an example of the default
file format.

To manually enter a puzzle, move the cursor to required positions and type
in the desired digits; to clear puzzle positions, use the SPACE, minus,
zero, or period keys. Any digit or any of the SPACE, minus, zero, or period
keys also advances the cursor to the next puzzle position, making it
reasonably easy to use the keypad (with Num Lock ON) to enter puzzles.

Solution Mode
-------------

In Solution Mode, the operator solves the puzzle as described above. In
this mode, a 5x2 character cell is used for each puzzle position, and
within this character cell, 

   - if the puzzle position has been resolved, either in the original
     puzzle or by the operator, the "answer" digit is displayed in YELLOW
     in the top middle character of the cell, and the period character is 
     displayed in LIGHT GRAY the remaining cell positions.

   - if the puzzle position had NOT not yet resolved, candidates for that
     position are displayed in LIGHT GRAY in their assigned locations within
     the cell.

Undo/Redo
---------

In Solution Mode, the program keeps track of changes due to operator action
as well as to program recalculation of candidate data; the operator can
'undo' the effects of any of his actions, along with the attendant effects
caused by candidate recalcuation, by hitting the PageUp key. The PageDown
key can be used to 'redo' 'undone' changes, but only until the first new
operator entry.

Hints
-----

In Solution Mode, the operator can obtain for "hints" as to how he might 
proceed at any time. A "normal" hint requires the operator to carefully 
consider the displayed candidate data before acting; a "blatant" hint
pinpoints a suggested action, and also momentarily displays certain
candidate data in special colors to suggest what should be done and why.
Special colors are as follows:

    White: candidates that should not be promoted or excluded themselves,
           but whose configuration within the other elements of the puzzle
           suggest something about the other candidates.
    Green: candidates that should be promoted.
      Red: candidates that should be excluded.
      
Solve It! 
---------

A "solve it" facility is provided in Solution Mode to completely solve a
puzzle and display the calculated solution. Two things should be noted
about this facility:

   1) All user (Solve Mode) changes are discarded before the solution is
      calculated;
   2) The calculated solution may be WRONG if the initial puzzle is not
      consistant. To see how this can happen, use a text editor to create a
      puzzle with ONLY these two positions filled: a '1' in both the top
      and bottom positions in the leftmost column; then have the program
      calculate the solution.

Verify It 
---------

A "verify it" facility is provided in Solution Mode to check a puzzle
solution. If missing digits or multiple occurances of digits within any
row, column, or box, are found, these errors will be reported one at a time.


                       **** end of help ****