Hans writes > LaTeX already has several very slow commands with slow parsing, for > example the variations of "new" with the LaTeX special style of defining > arguments. Having a definition command that is slower than def is acceptable. Having a mechanism where the _use_ of commands is an order of magnitude (or more) slower than directly calling a control sequence is not acceptible, as long as the system is to be programmed in TeX (or a TeX-like system such as etex or omega). This means that while it might be useful sometimes to `parse out' the argument specification from the command name this would only ever be used in limited circumstances, eg to define one variant form in terms of another if for some reason the normal `base' NNNN (or nnnn) form is for some reason unavailable. As Javier commented the current N-n distinction is not always perfect. The exact detail of the conventions may well need changing, but the basic principle must be that command sequences are accessed directly as tokens at the level we are talking about (which is the low level programming conventions in which higher level markup can be defined). This does not mean that the document level markup has to be token based. Already LaTeX has the environment constructs which are not. \begin{enumerate} is 12 tokens rather than \begingroup\enumerate which is two. The environment syntax can fairly easily be offered in an alternative syntax, say <enumerate> ... </enumerate> which is about the same in terms of speed and memory usage as \begin \end (you have to work a bit harder to get a full XML system though:-). Having the document level markup being something that is parsed, `by hand', using a parser written in TeX is acceptable, but only if the result of that initial processing is a set of command tokens that can be executed in the normal way of command tokens directly looked up in TeX's hash table. I mention this point (again) not to try to stifle discussion but because I got rather lost at what level you are intending some of your module proposals to be used. David