Xerox Paris, a document system Support & Software 사용자 가이드

As we have just pointed out, the carriage-return byte is normally superfluous and
could be ignored. Although in some cases print lines will be terminated by a single
line-feed byte only, the majority of cases will still use the carriage-return, line-feed
pair of bytes. This is because most print files are still conditioned to print to a
simple line printer.

These line printers are really just automated typewriters and produce very simple
pages. Formatting of the page is limited due to the mono-spaced (fixed pitch)
character set, however they usually do include a ‘bolding’ function to highlight
various elements of the page. Bolding is achieved simply by overprinting a line (or
portion of a line) to obtain the effect of a darker impression.

The method used to achieve bolding involves a single carriage-return byte as
follows:

The line (or portion of the line) to be bolded needs to be printed twice (in
some cases more than twice). The second time must be exactly over the top
of the previous line - hence the term ‘over-printing’. Therefore, while most
lines will be terminated by a carriage-return and line feed pair, lines to be
over-printed will be terminated by a single carriage-return only.

It is in these instances where we need to act on the carriage-return byte.

It is very important to honor these over-print lines, otherwise the line count will be
affected. Although laser printers can overprint, they do not involve the impact of a
hammer and are more accurate, with the result that an overprinted line will be
indiscernible from a normal (single) line.

While the over-print lines are being honored, some other method of bolding will be
required. Bolding is normally just a change to a new font (or the bold version of the
current font) and must be achieved either by Local Text Block Font Change events
(Chapter 7 of the PARIS Designer User’s Manual

), or by the use of font indexes

(‘How does Font Indexing work

’ on page 133).