diff --git a/css-values-3/Overview.bs b/css-values-3/Overview.bs
index 2e3b8600701..78e082906f3 100644
--- a/css-values-3/Overview.bs
+++ b/css-values-3/Overview.bs
@@ -1740,8 +1740,12 @@ Range Checking
Parse-time range-checking of values is not performed within ''calc()'',
and therefore out-of-range values do not cause the declaration to become invalid.
- However, the used value resulting from an expression
+ However, the value resulting from an expression
must be clamped to the range allowed in the target context.
+ Clamping is performed on computed values to the extent possible,
+ and also on used values
+ if computation was unable to sufficiently simplify the expression
+ to allow range-checking.
Note: This requires all contexts accepting ''calc()''
to define their allowable values as a closed (not open) interval.
@@ -2140,6 +2144,9 @@ Changes
Reverted previous change to allow zero angles to drop their unit;
this will instead be special-cased where needed for backwards-compatibility.
(See discussion)
+ Defined that range checking, and any resulting clamping, of ''calc()'' values
+ is performed both at computed time and at used time.
+ (Issue #434)
Fixed grammar error that disallowed numeric expressions as denominators in ''calc()''.
(Issue 12)
Defined handling of font-relative units outside the context of an element.
diff --git a/css-values-4/Overview.bs b/css-values-4/Overview.bs
index 0beb0957b50..c6fa89cd4c3 100644
--- a/css-values-4/Overview.bs
+++ b/css-values-4/Overview.bs
@@ -1880,8 +1880,12 @@ Range Checking
Parse-time range-checking of values is not performed within [=math functions=],
and therefore out-of-range values do not cause the declaration to become invalid.
- However, the used value resulting from an expression
+ However, the value resulting from an expression
must be clamped to the range allowed in the target context.
+ Clamping is performed on computed values to the extent possible,
+ and also on used values
+ if computation was unable to sufficiently simplify the expression
+ to allow range-checking.
Note: This requires all contexts accepting ''calc()''
to define their allowable values as a closed (not open) interval.