Arthur Reutenauer wrote:
And just for curioisty, where such names as Mark II and Mark IV come from?
% engine=luatex language=uk \startcomponent mk-iitoiv \environment mk-environment \chapter{From \MKII\ to \MKIV} Sometime in 2005 the development of \LUATEX\ started, a further development of \PDFTEX\ and a precursor to \PDFTEX\ version~2. This \TEX\ variant will provide: \startitemize[packed] \item 21--32 bit internals plus a code cleanup \item flexible support for \OPENTYPE\ fonts \item an internal \UTF\ data flow \item the bidirectional typesetting of \ALEPH \item \LUA\ callbacks to the most relevant \TEX\ internals \item some extensions to \TEX\ (for instance math) \item an efficient way to communicate with \METAPOST \stopitemize In the tradition of \TEX\ this successor will be downward compatible in most essential parts and in the end, there is still \PDFTEX\ version~1 as fall back. In the mean time we have seen another unicode variant show up, \XETEX\ which is under active development, uses external libraries, provides access to the fonts on the operating system, etc. From the beginning, \CONTEXT\ always worked with all engines. This was achieved by conditional code blocks: depending on what engine was used, different code was put in the format and|/|or used at runtime. Users normally were unaware of this. Examples of engines are \ETEX, \ALEPH, and \XETEX. Because nowadays all engines provide the \ETEX\ features, in August 2006 we decided to consider those features to be present and drop providing the standard \TEX\ compatible variants. This is a small effort because all code that is sensitive for optimization already has \ETEX\ code branches for many years. However, with the arrival of \LUATEX, we need a more drastic approach. Quite some existing code can go away and will be replaced by different solutions. Where \TEX\ code ends up in the format file, along with its state, \LUA\ code will be initiated at run time, after a \LUA\ instance is started. \CONTEXT\ reserves its own instance of \LUA. Most of this will go unnoticed for the users because the user interface will not change. For developers however, we need to provide a mechanism to deal with these issues. This is why, for the first time in \CONTEXT's history we will officially use a kind of version tag. When we changed the low level interface from Dutch to English we jokingly talked of version~2. So, it makes sense to follow this lead. \startitemize[packed] \item \notabene {\CONTEXT\ \MKI}\quad At that moment we still had a low level Dutch interface, invisible for users but not for developers. \item \notabene {\CONTEXT\ \MKII}\quad We now have a low level English interface, which (as we indeed saw happen) triggers more development by users. \item \notabene {\CONTEXT\ \MKIV}\quad This is the next generation of \CONTEXT, with parts re||implemented. It's an at some points drastic system overhaul. \stopitemize Keep in mind that the functionality does not change, although in some places, for instance fonts, \MKIV\ may provide additional functionality. The reason why most users will not notice the difference (maybe apart from performance and convenience) is that at the user interface level nothing changes (most of it deals with typesetting, not with low level details). The hole in the numbering permits us to provide a \MKIII\ version as well. Once \XETEX\ is stable, we may use that slot for \XETEX\ specific implementations. As per August 2006 the banner is adapted to this distinction: \starttyping ... ver: 2006.09.06 22:46 MK II fmt: 2006.9.6 ... ... ver: 2006.09.06 22:47 MK IV fmt: 2006.9.6 ... \stoptyping This numbering system is reflected at the file level in such a way that we can keep developing the way we do, i.e.\ no files all over the place, in subdirectories, etc. Most of the system's core files are not affected, but some may be, like those dealing with fonts, input- and output encodings, file handling, etc. Those files may come with different suffixes: \startitemize \item \type {somefile.tex}: the main file, implementing the interface and common code \item \type {somefile.mkii}: mostly existing code, suitable for good old \TEX\ (\ETEX, \PDFTEX, \ALEPH). \item \type {somefile.mkiv}: code optimized for use with \LUATEX, which could follow completely different approaches \item \type {somefile.lua}: \LUA\ code, loaded at format generation time and|/|or runtime \stopitemize As said, some day \type {somefile.mkiii} code may show up. Which variant is loaded is determined automatically at format generation time as well as at run time. \stopcomponent ----------------------------------------------------------------- Hans Hagen | PRAGMA ADE Ridderstraat 27 | 8061 GH Hasselt | The Netherlands tel: 038 477 53 69 | fax: 038 477 53 74 | www.pragma-ade.com | www.pragma-pod.nl -----------------------------------------------------------------