[css-transforms-1] Define reference box for paint servers and clipPath element. #892

Author: dirkschulze

css-transforms-1/Overview.bs

@@ -141,7 +141,7 @@ When used in this specification, terms have the meanings assigned in this sectio
     :: A transformable element is an element in one of these categories:
         * all elements whose layout is governed by the CSS box model except for non-replaced inline boxes, table-column boxes, and table-column-group boxes [[!CSS2]],
 
-        * all SVG <a>paint server elements</a> and SVG <a>renderable elements</a> with the exception of any descendant element of <a>text content elements</a> [[!SVG2]].
+        * all SVG <a>paint server elements</a>, the <a element>clipPath</a> element and SVG <a>renderable elements</a> with the exception of any descendant element of <a>text content elements</a> [[!SVG2]].
 
     : <dfn>transformed element</dfn>
     :: An element with a computed value other than ''transform/none'' for the 'transform' property.
@@ -445,7 +445,11 @@ All transformations defined by the 'transform' and 'transform-origin' property a
     Issue(w3c/csswg-drafts#999): Follow used value definition of Fill and Stroke specs/SVG2?
 </dl>
 
-Issue(w3c/csswg-drafts#892): Clarify what the reference box of paint servers, <a element>clipPath</a> and <a element>mask</a> is.
+For the SVG <{pattern}> element, the reference box gets defined by the <{pattern/patternUnits}> attribute [[!SVG2]].
+
+For the SVG <a element>linearGradient</a> and <a element>radialGradient</a> elements, the reference box gets defined by the <{linearGradient/gradientUnits}> attribute [[!SVG2]].
+
+For the SVG <a element>clipPath</a> element, the reference box gets defined by the <{clipPath/clipPathUnits}> attribute [[!CSS-MASKING]].
 
 A reference box adds an additional offset to the origin specified by the 'transform-origin' property.
 
@@ -1468,6 +1472,7 @@ The following changes were made since the <a href="https://www.w3.org/TR/2017/WD
 * Define target coordinate space for transformations on <{pattern}>, <{linearGradient}>, <{radialGradient}> and <{clipPath}> elements.
 * Remove 3-value <<rotate()>> from transform function primitives.
 * Be more specific about computation of [=transformation matrix=] and [=current transformation matrix=].
+* Define reference box for paint servers and <{clipPath}> element.
 * Editorial changes.
 
 <h2 class=no-num id='acknowledgments'>Acknowledgments</h2>