What's the right way to typeset the phrase "x-y plane" in US English? A full sentence example would be something like:

Our new detector has incredible resolution in the x-y plane, but provides no position information in the z direction.

A few options I can think of are:

$x-y$ plane
$x$-$y$ plane
$x$ - $y$ plane
$x$--$y$ plane
$x$ -- $y$ plane
  • I voted to close because it has nothing to do with Latex. Nevertheless, I would write: xy plane. – Dr. Manuel Kuehner Jul 22 '19 at 23:41

The "-" is a hyphen and should thus neither be in math mode (where it is a minus), surrounded by spaces or typeset as an en-dash. Thus

$x$-$y$ plane

is the one.

Even better, making sure that no line breaks occur inside the phrase:


with amsmath loaded. Since this is a bit verbose, you may want to define a macro for this.

  • Interesting. I would have put my money on the en-dash, because that's the one used for spans. – SU3 Jul 22 '19 at 17:59
  • An answer here also suggests en-dash. – SU3 Jul 22 '19 at 23:02
  • 1
    @SU3 Hmm, interesting. It seems unwise to me to blend en-dashes with hyphens, but it does indeed seem to be common in English literature. However, a quick web search did not yield any examples of "x-y plane" at all. It seems that "xy plane" or "XY plane" are far more common. If you want to go with the pack, you should probably go with one of those (maybe with pointers from egreg's answer. If you want to stick with "x-y plane", I would still stick to the hyphen, though it seems to be debatable if an en-dash is an alternative. – schtandard Jul 22 '19 at 23:28
  • For posterity, here's the command I've decided to use: \newcommand{\plane}[2]{$#1$\nobreakdash-$#2$~plane\xspace}. The \xspace makes sure there's a break between plane and the next word, if it appears in the middle of a sentence. – SU3 Jul 23 '19 at 13:51

Not the answer you're looking for? Browse other questions tagged or ask your own question.