IBM 1725 SLS - Manual (Page 281)

Sessions
D-7 Sessions
Examples
End by Count Example
For the end-by-count method of signaling the end of a subjob using a
length, the byte count begins after the terminator following the
%%Session: ... sequence. For example, counting starts with %! as
the first 2 bytes in the following example:
%%Session: 0 65535
%!
%%IncludeFeature: emulation(postscript)
...
...
» Note: When using this method, include all white space and forms control
characters inserted by the host system in the byte count.
End by Delimiter String Example
To group the three subjobs in the following example into a document
using the end-by-delimiter string method, the new combined data
stream may look like this:
» Note: Text in the Tekton typeface is comment, not part of the data stream.
Open connection: data comes into the printer
%%Session: 5 null
%!
%%IncludeFeature: emulation (postscript)
%%EndComments
...
PostScript data
%%EndSubJob
%%Session: 4%%End2ndSubJob
%!
%%IncludeFeature: emulation (pcl5)
%%EndComments
...
PCL 5 data
...