PRESCRIBE Command Reference
240
RVRD — ReceiVe Raster Data
Format
RVRD; number of data, data, ... ;
Function
The RVRD command declares the start of raster data. Raster data represents dot lines
encoded as numeric values as shown below. Each dot line is divided into 8-dot segments.
Each segment is converted to a number by the same system of column weights as used in
the FPAT (Fill PATtern) command.
The first segment in the example above encodes to 7 as follows:
0+0+0
+
0+0+4+2+1 = 7
The second segment encodes similarly to 192:
128+64+0+0+0+0+0+0 = 192
In the printing system command language, the segments are being treated as bytes of
data in which the black dots are 1s and the white dots are 0s. The raster data values are
the decimal values of the bytes.
Each line of raster data starts with a positive integer (1 to 511) indicating the number of
segments in the line (2 in the example shown). The raster data follows, separated by
commas. Each data value is an integer from 0 to 255. A semicolon ends the line. Spaces
occurring anywhere in the line are ignored.
Carriage returns following commas are also ignored, so long as raster lines can be broken
up if necessary, as shown below. The carriage return must be placed after a comma, as
follows:
34, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1;
There are no limits on the length of a raster line or the number of lines.
Zeros can be omitted, retaining only the delimiting commas. For zeros at the end of the
line, the commas can also be omitted. The following example displays equivalent raster
data lines:
7, 0, 0, 15, 0, 15, 0, 0; and 7, , , 15, , 15;
The following example demonstrates two ways to produce a blank raster line:
1, 0; or 1, ;
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