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4.4.3 Defining the space and column
Before you useprintpositioningcommands, you firstmay wanttochangethe
definitions of the line or space (sometimes called “vertical and horizontal
motion indexes”, VMI and HMI). These definitions don’t actually move the
print position. Instead, they define two basic units you can use in print
position commands.
What’s important about the space isthat itdefines how far the print position
travels for every character you print (except for proportionally spaced text).
The space can also be thoughtof as the width ofa vertical print column. One
column width isthe width ofthespacecharacter in thecurrent font,no matter
whether it is monospaced or proportionally spaced.
Occasionally you may want to change space width to override the current
pitch setting. Let’s look at an example. The space width comes in units of
l/120th ofan inch,and theCourierfontcan print 10charactersperinch.Each
character covers a tenth — 12/120ths— of an inch, so that font’s default
space width is 12 units. If we change its space width to 6, each character
would half-overlap the one before it.
If you are using <S1>and <SO> to shift between a primary and secondary
font, it’s a good idea to change the space width after every shift.
To change the space width you send this command:
,<ESC> &k n H
in which for n you can enter a number from O(zero)to 840. A width of Owill
print characters on top of each other; a width of 840 will print them seven
inches apart.
4.4.5 Defining line depth
The linedep[h(sometimes called the “vertical motion index”) specifieshow
far down apagetheprintpositionwillmoveforeach linefeed. You probably
won’t use the line depth as much as lines-per-inch. Line depth can be more
precise but it isn’t as easy to calculate. The line depth comes in multiples of
l/48th of an inch.
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