APPLICATION NOTE #106:
 USING XYWRITE'S HORIZONTAL MOTION FEATURE
 Rev. 06


 To support certain printers that cannot do proportional spacing, 
XyWrite provides the Horizontal Motion feature. This feature uses an 
HM (Horizontal Motion) table in the printer file to define increments 
of the printer's horizontal motion index and a DEFAULT setting that 
defines when the actual printer escapement takes place.


 HM TABLE
 The HM table in the printer file is similar to the CP (Character 
Pitch) table used by microjustification. The first line contains a 
value equal to the number of lines in the table. The balance of the 
table contains the printer codes that set the character pitch of the 
printer. This information, called the horizontal motion index, is 
found in your printer manual.

 For example, the HM table for a NEC 7710 printer looks like this:

     HM:12
     {ESC}]A
     {ESC}]B
     {ESC}]C
     {ESC}]D
         .
         .
         .
     {ESC}]L

 You must have at least as many increments in the HM table as the 
width of the widest character.

 When you TYPE a document, XyWrite looks in the width table to 
determine the width of each character and then uses the information 
in the HM table to determine the amount of space the printer should 
escape when it types a character.


 DEFAULT HM COMMAND
 When a character is printed, it forms an invisible box. The DEFAULT 
HM command determines where a character is positioned within that 
invisible box. You can actually change the way type looks by changing 
the setting of this command. The settings are:

   default hm=1   Places the character to the left of the character 
box. It
                  does this by sending a code to the printer that 
tells it to
                  output the character and then escape the full amount 
(as
                  defined by the width of the character and the HM 
table).


    default hm=2  Centers the character in the character box. It does 
this by
                  using an escapement value that is the average of two
                  characters. For example, for the letter combination 
HM,
                  XyWrite sends the following sequence of instructions 
to the
                  printer:

                    Escape 1/2 width of character H
                    Set character H
                    Escape 1/2 width of character H plus 1/2 width of
                    character M
                    Set character M

   default hm=0   Ignores the HM table. This is the default value.


 SUBSTITUTION TABLE
 Proportional print wheels frequently use different character 
positions than monospace print wheels. Most printers have a switch 
setting that indicates which type of print wheel is in use. If you 
are using a proportional print wheel on a printer that is not 
designed to support proportional fonts, you may need to create a 
substitution table.