Syntax for multidimensional arrays

NEWS.md

@@ -11,6 +11,11 @@ New language features
   as `.&&` and `.||`. ([#39594])
 * `⫪` (U+2AEA, `\Top`, `\downvDash`) and `⫫` (U+2AEB, `\Bot`, `\upvDash`, `\indep`)
   may now be used as binary operators with comparison precedence. ([#39403])
+* Repeated semicolons may now be used inside array literals to separate dimensions of an array,
+  with the number of semicolons specifying the particular dimension. Just as the single semicolon
+  in `[A; B]` has always described concatenating along the first dimension (vertically), now two
+  semicolons `[A;; B]` do so in the second dimension (horizontally), three semicolons `;;;` in the
+  third, and so on. ([#33697])
 
 Language changes
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