[css-values-4][editorial] Use the Infra term 'implementation-defined' rather than 'undefined'. #8865

Author: tabatkins

css-values-4/Overview.bs

@@ -1196,13 +1196,13 @@ Numeric Data Types</h2>
 	whose usage is more localized.
 
 	The precision and supported range of numeric values in CSS
-	is <em>explicitly undefined</em>,
+	is [=implementation-defined=],
 	and can vary based on the property or other context a value is used in.
 	However, within the CSS specifications,
 	infinite precision and range is assumed.
 	When a value cannot be explicitly supported due to range/precision limitations,
 	it must be converted to the closest value supported by the implementation,
-	but how the implementation defines "closest" is explicitly undefined as well.
+	but how the implementation defines "closest" is [=implementation-defined=] as well.
 
 	If an <<angle>> must be converted
 	due to exceeding the implementation-defined range of supported values,
@@ -1724,7 +1724,7 @@ Distance Units: the <<length>> type</h2>
 
 	While the exact supported precision of numeric values,
 	and how they are rounded to match that precision,
-	is generally intentionally undefined,
+	is generally [=implementation-defined=],
 	<<length>>s in 'border-width' and a few other properties
 	are rounded in a specific fashion
 	to ensure reasonable visual display.
@@ -2062,7 +2062,7 @@ Font-relative Lengths: the ''em'', ''rem'', ''ex'', ''rex'', ''cap'', ''rcap'',
 
 	Some user-agents apply restrictions to the 'line-height' values on form controls.
 	These must have no effect on the ''lh'' and ''rlh'' units.
-	The effect on their descendants, however, is undefined.
+	The effect on their descendants, however, is [=implementation-defined=].
 
 <!--
 ██     ██ ██      ██       ██ ████████ ████████  ██████
@@ -3457,7 +3457,7 @@ Argument Ranges</h4>
 
 	In ''tan(A)'', if A is one of the asymptote values
 	(such as ''90deg'', ''270deg'', etc),
-	the result is <strong>explicitly undefined</strong>.
+	the numeric result is [=implementation-defined=].
 	If an implementation is capable of exactly representing these inputs,
 	it <em>should</em> return
 	+∞ for the asymptotes at <code>90deg + N*360deg</code>,
@@ -3470,7 +3470,7 @@ Argument Ranges</h4>
 	for these inputs.
 
 	<details class=note>
-		<summary>Why are these undefined?</summary>
+		<summary>Why are these [=implementation-defined=]?</summary>
 
 		The tangent function is <em>discontinuous</em> at its asymptotes:
 		it approaches infinity from one side