Evolution of Master Source Formats
Plain text was the first master source type/format for Project Gutenberg, and remains important today. Plain text is readable on any device. Plain text is printable, and efficient to store (including for compression, or sharing by email). For decades, the International Standards Organization has provided standard computerized encoding for the basic American standard codes (ASCII) and extensions for accents and other special characters (Latin1 or ISO 8859-1). Encoding exists for other languages, and Unicode (with 8- and 16-bit variations) provides encoding for larger groups of characters.
Within the first few hundred Project Gutenberg eBooks, some encoding was offered which seemed promising, but did not withstand the test of time. An early PostScript file was rendered unusable due to insertion of the Project Gutenberg standard header; a dictionary included markup that, today, might be reminiscent of XML or ReStructured Text, but without any sort of codebook for proper presentation; a few word processor native formats, including WordStar and WordPerfect, were used but are no longer readable with modern computers.
Even HTML (and other XML variants) was viewed with skepticism, since the longevity of formats is notoriously difficult to predict when they first become available.
For these reasons, Project Gutenberg still prefers to make plain text available for essentially every eBook. The only exceptions are those for which no plain text encoding is reasonable — such as Chinese, or mathematical texts, or music. In this way, the collection is “future proof,” so that even if all content cannot be fully represented as text, the files themselves will still be readable and enjoyable to read.
Figure 3: Typical text view, showing fixed-length lines and spacing among components.
"A CONNECTICUT YANKEE IN KING ARTHUR'S COURT"
by MARK TWAIN (Samuel L. Clemens)
PREFACE
The ungentle laws and customs touched upon in this tale are
historical, and the episodes which are used to illustrate
them are also historical. It is not pretended that these
laws and customs existed in England in the sixth century;
no, it is only pretended that inasmuch as they existed in
the English and other civilizations of far later times, it
is safe to consider that it is no libel upon the sixth
century to suppose them to have been in practice in that day
also. One is quite justified in inferring that whatever one
of these laws or customs was lacking in that remote time,
its place was competently filled by a worse one.
Today, Project Gutenberg’s plain text offerings are most often derived automatically from another master format. The most common master format is HTML, which offers advantages of ubiquity and ease of authoring. LaTeX is also used as a master, mainly for mathematical texts. ReStructured Text (RST) was encouraged by Project Gutenberg, due to the ease of conversion to other formats. However, RST has not been widely adopted by eBook producers.