User's Manual

DEC PDP-11 TAPES
XEROX LASER PRINTING SYSTEMS TAPE FORMATS MANUAL 15-3
ANSI labeled tapes
The above format may optionally be bracketed by standard ANSI
labels conforming to the requirements of the ANSI standard X3.27
(see the ANSI tape section at the beginning of this manual).
Data formats
The processing involved by HOST=RSX11 handles tapes having the
following characteristics:
1. Variable record length
2. Data portion of records terminated by a carriage-related control
code (see table 15-3)ASCII character code
3. ASCII character code
4. Records may span blocks.
5. The format for such tapes actually created on a DEC system is
referred to as “FLX.”
Data structure characteristics
The data in the record can be thought of as one long stream of
characters processed serially by the printer. The stream consists of
two types of characters: printable characters and control codes.
Processing of printable characters and
control codes
Printable characters are accumulated until either a specified line
length has been reached or one of the carriage-related control codes
is encountered. The carriage-related control codes are intercepted
and used to initiate the appropriate function, such as print or skip to
channel. There can be several consecutive control codes with no
intervening printable data. If the number of printable characters
exceeds the defined print line length, the accumulated line is printed
followed by a space to the next line. The next data character is used
as the first character of the following print line.
The output stream is typically batched onto the tape at 512
characters per block. Any print line and its associated control code
may span from one block to the next.
Null characters Null characters (octal zero) may appear any place in the stream of
characters. The nulls are discarded and are not considered in any
computation of print line length. Additionally, nulls do not terminate
the characters being accumulated as a print line.
Number of bytes selected for printing Generally, all of the printable characters are intended to be printed.
The exception to this is noted in the “FONTINDEX” section. With all
other types of data extraction, the second parameter of the DATA=
statement controls the number of bytes to be selected for printing. In
the RSX11 data extraction process, the second parameter of the
DATA= option indicates the number of bytes to be selected for
printing on a given line. If the record is longer than that value, the
following portion is printed on the next line.