check

book.tex

@@ -17912,7 +17912,7 @@ Compile \ALLOCCLOS{\itm{len}}{\itm{type}}{\itm{arity}} in almost the
 same way as the \ALLOC{\itm{len}}{\itm{type}} form
 (section~\ref{sec:select-instructions-gc}). The only difference is
 that you should place the \itm{arity} in the tag that is stored at
-position $0$ of the vector. Recall that in
+position $0$ of the tuple. Recall that in
 section~\ref{sec:select-instructions-gc} a portion of the 64-bit tag
 was not used. We store the arity in the $5$ bits starting at position
 $58$.