Specifications

CHAPTER 3
LaserWriter Pro Software
Page Size Compatibility Operators 71
The conversions shown in Tables 3-25 and 3-26 provide the best possible compatibility
with PostScript Level 1 behavior. However, in several cases, no correct choice is possible.
For example, in Level 1 there is no support for 7 data bits with no parity, where the total
number of data and parity bits is 7. The Level 2 setting of 7 bits None is imperfectly
mapped to 7 bits mark. Most serial hardware does not support 8 bit Mark or 8 bit Space,
and therefore, these values are never generated in mapping from Level 1 to Level 2. In
fact, in Level 1, 8 bits mark and 8 bits space actually provide the equivalent of the Level 2
8 bits None functionality.
Page Size Compatibility Operators 3
The page size operators are in the user dictionary, userdict. Each operator requests a
specific paper size and imaging box. See Table 3-27 on page 72. The operators use the
sizes indicated in the table as a page device PageSize parameter. All operators set
PageSizePolicy to 7, which guarantees that the imaging area established is correct
for the size requested, regardless of which paper tray is chosen.
The only error generated is limitcheck, which is occurs when there is not sufficient
memory for the imaging area requested.
The note operator modifies the current page device settings by establishing an
ImagingBBox parameter of [25 25 width minus 25 height minus 25] if the current
PageSize parameter is [width height].
Table 3-26 Device parameters-to-options conversion
DataBits and Parity Data bits and parity
Level 2 Level 1
7 bits None 7 bits mark
7 bits Space 7 bits space
7 bits Mark 7 bits mark
7 bits Odd 7 bits odd
7 bits Even 7 bits even
8 bits None 8 bits mark
8 bits Space 8 bits space
8 bits Mark 8 bits mark
8 bits Odd 8 bits odd
8 bits Even 8 bits even