diff --git a/spec.html b/spec.html
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+++ b/spec.html
@@ -39805,6 +39805,9 @@
Then for all non-negative integers _j_ and _k_, each less than _itemCount_, if ℝ(_SortCompare_(old[_j_], old[_k_])) < 0, then π(_j_) < π(_k_).
+
+ And for all non-negative integers _j_ and _k_ such that _j_ < _k_ < _itemCount_, if ℝ(_SortCompare_(old[_j_], old[_k_])) = 0, then π(_j_) < π(_k_); i.e., the sort is stable.
+
Here the notation old[_j_] is used to refer to _items_[_j_] before step is executed, and the notation new[_j_] to refer to _items_[_j_] after step has been executed.
An abstract closure or function _comparator_ is a consistent comparator for a set of values _S_ if all of the requirements below are met for all values _a_, _b_, and _c_ (possibly the same value) in the set _S_: The notation _a_ <C _b_ means ℝ(_comparator_(_a_, _b_)) < 0; _a_ =C _b_ means ℝ(_comparator_(_a_, _b_)) = 0; and _a_ >C _b_ means ℝ(_comparator_(_a_, _b_)) > 0.