Postscript supports the concept of page sets. The page sets are defined by the parameters NumCopies and Collate. When multiple copies of a document are requested (NumCopies > 1), the pages are delivered to the output destination in page sets. The boolean value of the Collate parameter determines the make-up of these sets and thus the order in which the pages are delivered:
When Collate is true, each page set contains one complete copy of the entire document. One copy of each page, with the pages arranged in the correct order. The number of delivered page sets is equal to the requested number of copies.
When Collate is false, each page set contains the requested number of copies of each single page of the document. The number of delivered page sets is equal to the number of pages in the document.
From the PS concept of page sets, the concept of subsets is derived from handling independent outputs for parts of the PS file. Page device parameters that normally apply to page sets are used for subsets.
When you change the value of one the following page device parameter, a new subset is created:
Staple
StapleDetails
Collate
Jog
Outputtype
Number of copies
Bind
BindDetails
Toggle the value to create two successive subsets with the same characteristics.
Example:
<< /Staple 0>> setpagedevice
<< /Staple 3>> setpagedevice
For the new subset, the values for the other parameters remain equal as for the previous subset if they are not specified again. If the following values are set:
/Staple 3,
/Jog 3, or
/Collate true
they are applied for EACH set, even if the values are set once at the beginning of the file.