Possible typo in Markowitz (1952) “Portfolio Selection” illustration?

I am reading Harry Markowitz’s “ Portfolio Selection ” ( Journal of Finance , 1952), and I cannot determine whether Figure 4 contains a labeling error or whether I am misunderstanding the paper. On PDF page 11 (journal page 86), Figure 4 shows a three-dimensional coordinate system with axes $X_1$ , $X_2$ , and $X_3$ , together with three lines labeled $l_{1234}$ , $l_{234}$ , and $l_{124}$ . On the following page, Markowitz explains Figure 4 in footnote 10: The attainable set is represented, in three-space, by the tetrahedron... Let $S_{123}$ be the subspace consisting of all points with $X_4=0$ ... For each subspace $S_{a_1,\ldots,a_a}$ , we can define a critical line $l_{a_1,\ldots,a_a}$ ... If a point is in $S_{a_1,\ldots,a_a}$ and is efficient, it must be on $l_{a_1,\ldots,a_a}$ . My understanding is that each $l$ -line represents the efficient set within the corresponding subspace, and that its subscripts identify the securities that may have nonzero portfolio weights. If that interpretation is correct, $l_{124}$ should lie on the face where $X_3=0$ , because only securities 1, 2, and 4 are included. In Figure 4, however, $l_{124}$ appears to lie on the “floor” of the tetrahedron, where $X_1=0$ and $X_2$ , $X_3$ , and $X_4$ may be nonzero. That face would therefore seem to correspond to $S_{234}$ . Likewise, $l_{234}$ appears on the left face of the tetrahedron, where $X_3=0$ , which would seem to correspond to $S_{124}$ . The label $l_{1234}$ makes sense because that line passes through the interior of the tetrahedron, where all four portfolio weights may be nonzero. Does Figure 4 contain a typo, with the following labels accidentally reversed? $$ l_{234}\longleftrightarrow l_{124}