> Since what is happening is that "foo" is being added to a namespace, > would it not be logical for the usage to be: > \DeclareDocumentCommand foo {...}{...} ? You may want to describe it that way, but that isn't really the latex view. The latex view is that the name of the command is `\foo' not that \ is markup and the command is called `foo'. (What happens at the primitive TeX level is probably nearer the latter, but much of latex is concerned with hiding primitive tex notions with higher level constructs, so the implementation details are not really relevant here.) It would probably be \DeclareDocumentCommand {foo} {...}{...} ^ ^ as otherwise the exact syntax for what is the `foo' argument appears to be somewhat under specified. but while some things (environments, pagestyles, ...) are referred to by name (with no backslash), commands are always referred to by name starting with \. There are no user level constructs that use both of these forms. (Internal macros such as \@ifundefined do switch between these views). In latex the `name' of the \mbox command is `\mbox'. The fact that if you go \catcode`j=0 then jbox{this} also works as well as \mbox{this} is a technical detail that probably you don't want to highlight. David