I'm working with plots for which I'm finding the maximum point and labelling the x and y values at which it occurs:

enter image description here

My question is, is there an 'official' name for the red dashed lines that extend from the point to each of the axes?

  • $\begingroup$ Do you mean any set of vertical-and-horizontal reference lines that mark some particular chosen $x$ (abscissa) and its corresponding $y$, (ordinate) - not necessarily marking the functional-mode as in the diagram - or do you mean a term for the specific $x$-that-maximizes $y=f(x)$ (i.e. the argmax) and its corresponding $y$ (the function mode / maximum)? $\endgroup$
    – Glen_b
    Commented Oct 27, 2022 at 23:24
  • $\begingroup$ @Glen_b I meant in general, any set of horizontal and vertical lines marking a point. $\endgroup$
    – Jim421616
    Commented Oct 28, 2022 at 9:35
  • 1
    $\begingroup$ Personally, I tend to say "a pair of horizontal and vertical reference lines" but there may well be some other term. $\endgroup$
    – Glen_b
    Commented Oct 28, 2022 at 11:36
  • $\begingroup$ With a linear plateau model, the terms "critical x" and "plateau" are used. Here, you might use "critical x" and "maximum" ? Or maybe "model maximum" and "x corresponding to the model maximum" ? $\endgroup$ Commented Oct 28, 2022 at 16:20
  • $\begingroup$ @SalMangiafico I'm interested in the term for the red dashed reference lines extending to the axes, not the point they're highlighting. $\endgroup$
    – Jim421616
    Commented Oct 28, 2022 at 21:01

1 Answer 1


My own impression and the consensus here is that the answer is no, there is no specific name for these reference lines.


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