In this section I would like to discuss some parts of the implementation of the babel system. Not all code will be shown, because some parts of it are just series of slightly modified code from the standard document styles. The files are fully documented and interested readers can print them if they have access to the doc option, described by Frank Mittelbach.
The description of the macros that follows is based on an environment using TEX 3.x, together with a version of lplain.tex based on plain.tex version 3.x. The actual implementation allows for other situations as well, i.e a version of babel.sty for TEX 2.x will be available.