[css-transforms-2] Better specify the computed values of the translate/rotate/scale. Relates to w3c/fxtf-drafts#313

Author: tabatkins

css-transforms-2/Overview.bs

@@ -554,36 +554,41 @@ Initial: none
 Applies to: <a>transformable elements</a>
 Inherited: no
 Percentages: relative to the width of the containing block (for the first value) or the height (for the second value)
-Computed Value: as specified, with lengths made absolute
-Animatable: as <<length>> or <<percentage>> list
+Computed Value: the keyword ''translate/none'', or a list of 2 or 3 <<length-percentage>>s, with lengths made absolute
+Animatable: as <<length>> or <<percentage>> list, but see below for ''translate/none''
 </pre>
 
 The 'translate' property accepts 1-3 values,
 each specifying a translation against one axis,
 in the order X, Y, then Z.
-Unspecified translations default to ''0px''.
 
 If only one or two values are given,
 this specifies a 2d translation,
 equivalent to the ''translate()'' function.
+If the second value is missing,
+it defaults to ''0px''.
+
 If three values are given,
 this specifies a 3d translation,
 equivalent to the ''translate3d()'' function.
 
 <pre class="propdef">
 Name: rotate
-Value: none | [ x | y | z | <<number>>{3} ]? && <<angle>>
+Value: none | <<angle>> | [ x | y | z | <<number>>{3} ] && <<angle>>
 Initial: none
 Applies to: <a>transformable elements</a>
 Inherited: no
-Animatable: as SLERP
+Computed value: the keyword ''rotate/none'', or else see prose
+Animatable: as SLERP, but see below for ''rotate/none''
 </pre>
 
 The 'rotate' property accepts an angle to rotate an element,
 and optionally an axis to rotate it around.
 
 If the axis is omitted, this specifies a 2d rotation,
 equivalent to the ''rotate()'' function.
+In this case, the [=computed value=] of the property
+is a single <<angle>> value.
 
 Otherwise, it specifies a 3d rotation:
 if <dfn value for=rotate>x</dfn>,
@@ -595,6 +600,9 @@ Alternately, the axis can be specified explicitly
 by giving three numbers
 representing the x, y, and z components of an origin-centered vector,
 equivalent to the ''rotate3d()'' function.
+In this case, the [=computed value=] of the property
+is an <<angle>> and an axis,
+the latter consisting of a [=list=] of three <<number>>s.
 
 Note: While ''rotate: 30deg;'' and ''rotate: z 30deg;'' technically specify the same rotation,
 the first declaration is a 2d transform equivalent to ''transform: rotate(30deg);'',
@@ -607,7 +615,8 @@ Value: none | <<number>>{1,3}
 Initial: none
 Applies to: <a>transformable elements</a>
 Inherited: no
-Animatable: as <<number>> list
+Computed value: the keyword ''scale/none'', or a list of 2 or 3 <<number>>s
+Animatable: as <<number>> list, but see below for ''scale/none''
 </pre>
 
 The 'scale' property accepts 1-3 values,
@@ -633,7 +642,7 @@ which produces no transform at all.
 In particular,
 this value does <em>not</em> trigger the creation of a stacking context or [=containing block for all descendants=],
 while all other values
-(including identity transforms like ''translate: 0px'')
+(including “identity” transforms like ''translate: 0px'')
 create a stacking context and [=containing block for all descendants=],
 per usual for transforms.