I make use of a feature that in a project that consists of several files allows me to compile each LaTeX file individually, thus saving some compilation time while writing the manuscript. I think such a system might be useful for inclusion in LaTeX3. One way to view it is as a workaround for LaTeX's Pascal preamble style: If this preamble declaration style is dropped from LaTeX (replaced by a more OO system admitting local definitions), perhaps this feature I suggest would not be needed. So I use two files, "begin.tex" and "end.tex", and each text part file with in the project contains: \input begin ... % Text \input end The files "begin.tex" and "end.tex" look as follows (with some example user code): ------------------------------------------------------------- % File begin.tex: % \ifx\beginned\relax\message{file already read.}% \let\rebeginned\relax\let\mayendfileinput\endinput% \else\global\let\beginned\relax\let\mayendfileinput\relax\fi % \mayendfileinput % End or not end file input, as set above. % % Add user commands here below: \documentclass[leqno]{article} \usepackage{color} \usepackage{hyperref} % AMS Fonts Package \usepackage{amssymb} \usepackage{amscal} % Use AMS calligraphic instead of TeX. % AMS LaTeX Package \usepackage{amsmath} \usepackage{amscd} \usepackage{rsfs} % Use RSFS to define \mathscr \usepackage{abergmath} %\input hyphenations % Hyphenation file %\input definitions % Definitions file \begin{document} % EOF begin.tex --------------------------------------------------------------- % File end.tex: \ifx\rebeginned\relax\message{file: Not yet.}% \let\rebeginned\undefined\let\mayendfileinput\endinput% \else\message{file: Now.}\let\mayendfileinput\relax\fi % \mayendfileinput % End or not end file input, as set above. % % Add user commands here below: \end{document} %\end % EOF end.tex --------------------------------------------------------------- If one use the stuff above, then if say main.tex contains \input chapter1 \input chapter2 ... and all files, main.tex, chapter1, ..., contain the \input begin ... % text \input end pair, then the user defined commands of this pair will only be read once, so it becomes possible to compile each chapter1.tex, ... individually. However, LaTeX will be confused when later compiling main.tex because of multiply defined labels (but only on the level of warnings, I think). The idea would be to somehow integrate such a system into LaTeX, so that it works correctly with respect to labels, perhaps with a \begin{...} ... \end{...} pair replacing the \input being ... \input end stuff. Hans Aberg