[css-values-4][editorial] Slightly reword the automatic clamping text to make it clearer that it's often implicit/UA-defined.

Author: tabatkins

css-values-4/Overview.bs

@@ -5162,16 +5162,17 @@ Range Checking</h3>
 	(Clamping is not performed on <a>specified values</a>.)
 
 	Note: This requires all contexts accepting ''calc()''
-	to define their allowable values as a closed (not open) interval.
+	to define any range restrictions as closed (not open) interval endpoints:
+	"greater than or equal to 0px", not "greater than 0px" or "positive lengths".
 
-	Note: By definition,
-	±∞ are outside the allowed range for any property,
-	and will clamp to the minimum/maximum value allowed.
+	Note: While CSS intentionally leaves numeric precision/range UA-defined,
+	extremely large values (including, notably, ±∞)
+	will clamp to the minimum/maximum value allowed.
 	Even properties that can explicitly represent infinity as a keyword value,
 	such as 'animation-iteration-count',
 	will end up clamping ±∞,
 	as [=math functions=] can't resolve to keyword values;
-	the <em>numeric</em> part of the property's syntax still has a minimum/maximum value.
+	the <em>numeric</em> part of the property's syntax still has an implicit minimum/maximum value.
 
 	Additionally, if a [=math function=] that resolves to <<number>>
 	is used somewhere that only accepts <<integer>>,