Units of Measurement
Numbers that are used to specify dimensions
in form definitions and page definitions can be in any of five units of measurement. They are
specified in a command stream as follows:
- IN
- Inches
- MM
- Millimeters
- CM
- Centimeters
- POINTS
- Points are a common measurement in printing that are used to measure character height, as in 20-point type. A point is approximately 1/72 inch.
- PELS
- Equates to L-units. The number of pels per inch is a user-specified parameter. The default is 240 pels per inch.
These measurement units can be used in the SETUNITS command:
- LPI
- Lines per inch
- CPI
- Characters per inch
The parameters in PPFA that define a measurement can include any of the first five units of
measurement that are shown in the previous list. For example:
POSITION 1 IN 1 IN ;
or
POSITION 1 MM 1 MM ;
However, PPFA converts all measurements to logical units (L-units) as the common measurement.
(Normally, 1 inch equals 240 L-units, but this number can be changed by the user.) If a fraction
exists, the first decimal point is truncated. A SETUNITS command defines a unit of measurement that
is to be used as the default for any parameter that does not specify a dimension. This default is in
effect until another SETUNITS command is encountered. The following example shows part of a PPFA
command stream in which a SETUNITS command sets the units of measurement to one inch for a
subsequent POSITION (or OFFSET or LINEONE) subcommand.
SETUNITS 1 IN 1 IN ;
⋮
POSITION (or OFFSET or LINEONE) 1 1 ;
In the following example, SETUNITS can be used as a multiplier. The SETUNITS command sets
two-inch x and y default values. The POSITION
subcommand values are multiplied by the default values creating a position four inches horizontally
and four inches vertically from a given reference point. See SETUNITS Command
for a more detailed
explanation.
SETUNITS 2 IN 2 IN ;
⋮POSITION 2 2 ;