-\syntax{$x$@[$\alpha_1^1$ @! $\alpha_1^2$ $| \cdots |$ $\alpha_1^{m_1},
-\ldots,$ $\alpha_n^1$ @! $\alpha_n^2$ $| \cdots |$ $\alpha_n^{m_n}$@]}
-means exactly the same as \syntax{$x$@[$a_1, \ldots, a_n$@]} with the
-additional rules
+\syntax{$x$@[$\alpha_1^1$ | $\alpha_1^2$ | $\cdots$ | $\alpha_1^{m_1},
+\ldots,$ $\alpha_n^1$ | $\alpha_n^2$ | $\cdots$ | $\alpha_n^{m_n}$@]} means
+exactly the same as \syntax{$x$@[$a_1, \ldots, a_n$@]} with the additional
+rules