diff --git a/spec.html b/spec.html
index d06a85605a8..78d68411c55 100644
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+++ b/spec.html
@@ -1024,6 +1024,7 @@ Mathematical Operations
floor(_x_) = _x_ - (_x_ modulo 1).
+ An interval from lower bound _a_ to upper bound _b_ is a possibly-infinite, possibly-empty set of numeric values of the same numeric type. A numeric value _x_ is included in the interval if it satisfies the criteria _a_ < _x_ and _x_ < _b_. If the lower bound is described as inclusive, _a_ <e; _x_ is used instead of _a_ < _x_. If the upper bound is described as inclusive, _x_ <e; _b_ is used instead of _x_ < _b_. An inclusive interval is an interval where both bounds are inclusive. *NaN* is never included in an interval. An interval with an exclusive bound of *+0*𝔽 or *-0*𝔽 includes neither *+0*𝔽 nor *-0*𝔽. An interval with an inclusive bound of *+0*𝔽 or *-0*𝔽 includes both *+0*𝔽 and *-0*𝔽.