Today in the lounge was mentioned what was asserted to be a peculiarly British punctuational proclivity, the so-called "comash", that is to say, a comma, followed by a dash, with nothing between,—like that. The phenomenon was adduced in a sort of "that's crazy!" way (incidentally there's little I dislike more than the tic exhibited in this sentence, of, owing to lack of writerly skill, writing something like "in a 'actual description goes here' way": clearly one simply can't think of an elegant way to describe whatever), but really, doesn't it make a lot of sense? Punctuation marks can be very expressive, especially em dashes (my favorites!—maybe tied with semicola), so why ought one restrict their use to single isolated occurences? Surely in combination they can achieve heretofore undreamt-of degrees of subtlety in expression. (My gloss on the comash was that it implies a degree of reticence or hesitancy, and then:—suddenly elsewhere, or the dam is burst.)
It didn't take me long to come up, as I walked off, with the following silly and no doubt highly derivative series of thoughts. One might think that punctuation marks are designed for capturing (and, it wouldn't surprise me, perhaps were originally actually used to capture) vagaries of expression present in speech but not in a simple records of which mere words were uttered, and that, even so, the textual representation of a sentence can never capture the specificity of the spoken sentence (on which it would, then, logically depend), that, say, there's a digital/analog analogy to be made, such that no matter how frequent the samples, something is always missing. But that would be batty, because obviously what sorts of things you might mean ("mean" isn't really right, something more like the emphases you might intend ("intend" arguably not being an improvement), or, I guess, what you take yourself to be doing, or what you take yourself to want to do) in saying something (or communicating in some particular medium) will plainly be influenced by the notational/expressive possibilities afforded by writing/punctuation (or some other medium). The characteristic rhetorical possibilities of linking, for instance, in HTML, whose absence in some other medium might irk one. (Or consider the inability, in a representation allowing for real italics and in which italicization is the customary means of emphasis, of distinguishing between *this* *sort* of emphasis, in which each individual word gets its own distinct emphasis, and *this sort*, which operates on the whole phrase; this is something that bugs me once a month or so.) In that case, the punctuation marks, though perhaps introduced in order to capture something already present in whatever it is the writing system is supposed to encode, could easily take on writing-specific valences, which would then be exported into other media and become general; moreover, since the (new) expressive possibilities of the marks would be associated with easily manipulable signs, it could be possible simply by juxtaposing two of them to create (or at least render explicit) a possibly intended attitude useable in other media, so that the relation would be bidirectional. (Consider the interrobang. Actually don't, because I'm certainly not prepared to say that the familiar "what?!" was created by the mark, and not that the mark was created in response to a lack in the punctuation pantheon, though I am prepared to assert that there are probably now people who, when reacting what?!ly, think of their reaction in interrobangish terms, so maybe, sure, consider the interrobang.)
This is probably the familiar point about landscape painting teaching us how to look at nature recast, though. (Not (a) that I have any reason to believe that that was the first formulation of the general idea or (b) that plenty of people haven't gotten by recasting that point in a myriad of ways anyway.)
But I want to register my full support for the comma-dash, the semicolon-dash, the colon-dash, dashes of all sorts of lengths (consider Tristram Shandy), and all that. But the postscript is sacrosanct! Don't fuck with the postscript! No strategy! Boo strategy!