Clarify line cue setting specification. (#399)

index.bs

@@ -1873,15 +1873,16 @@ given:</p>
 </ol>
 
 <p class="note">A <a>WebVTT line cue setting</a> configures the offset of the cue box from the video
-viewport's edge in the direction opposite to the <a lt="WebVTT cue writing direction">writing
-direction</a>. For horizontal cues, this is the vertical offset from the top of the video viewport.
-The offset is for the <a lt="WebVTT cue line start alignment">start</a>, <a lt="WebVTT cue line
-center alignment">center</a>, or <a lt="WebVTT cue line end alignment">end</a> of the cue box,
-depending on the <a>WebVTT cue line alignment</a> value - <a lt="WebVTT cue line start
-alignment">start</a> by default. The offset can be given either as a percentage of the video
-dimension or as a line number. Line numbers are based on the size of the first line of the cue.
-Positive line numbers count from the start of the video viewport (the first line is numbered 0),
-negative line numbers from the end of the viewport (the last line is numbered &#x2212;1).</p>
+viewport's edge in the direction orthogonal to the <a lt="WebVTT cue writing direction">writing
+direction</a>. For horizontal cues, this is the vertical offset from the top of the video viewport,
+for vertical cues, it's the horizontal offset. The offset is for the <a lt="WebVTT cue line start
+alignment">start</a>, <a lt="WebVTT cue line center alignment">center</a>, or <a lt="WebVTT cue line
+end alignment">end</a> of the cue box, depending on the <a>WebVTT cue line alignment</a> value - <a
+lt="WebVTT cue line start alignment">start</a> by default. The offset can be given either as a
+percentage of the video dimension or as a line number. Line numbers are based on the size of the
+first line of the cue. Positive line numbers count from the start of the video viewport (the first
+line is numbered 0), negative line numbers from the end of the viewport (the last line is numbered
+&#x2212;1).</p>
 
 <p>A <dfn>WebVTT position cue setting</dfn> consists of the following components, in the order
 given:</p>

index.html

@@ -2870,13 +2870,13 @@ <h3 class="heading settled" data-level="4.4" id="cue-settings"><span class="secn
      </ol>
    </ol>
    <p class="note" role="note">A <a data-link-type="dfn" href="#webvtt-line-cue-setting" id="ref-for-webvtt-line-cue-setting-2">WebVTT line cue setting</a> configures the offset of the cue box from the video
-viewport’s edge in the direction opposite to the <a data-link-type="dfn" href="#webvtt-cue-writing-direction" id="ref-for-webvtt-cue-writing-direction-12">writing
-direction</a>. For horizontal cues, this is the vertical offset from the top of the video viewport.
-The offset is for the <a data-link-type="dfn" href="#webvtt-cue-line-start-alignment" id="ref-for-webvtt-cue-line-start-alignment-2">start</a>, <a data-link-type="dfn" href="#webvtt-cue-line-center-alignment" id="ref-for-webvtt-cue-line-center-alignment-1">center</a>, or <a data-link-type="dfn" href="#webvtt-cue-line-end-alignment" id="ref-for-webvtt-cue-line-end-alignment-1">end</a> of the cue box,
-depending on the <a data-link-type="dfn" href="#webvtt-cue-line-alignment" id="ref-for-webvtt-cue-line-alignment-5">WebVTT cue line alignment</a> value - <a data-link-type="dfn" href="#webvtt-cue-line-start-alignment" id="ref-for-webvtt-cue-line-start-alignment-3">start</a> by default. The offset can be given either as a percentage of the video
-dimension or as a line number. Line numbers are based on the size of the first line of the cue.
-Positive line numbers count from the start of the video viewport (the first line is numbered 0),
-negative line numbers from the end of the viewport (the last line is numbered −1).</p>
+viewport’s edge in the direction orthogonal to the <a data-link-type="dfn" href="#webvtt-cue-writing-direction" id="ref-for-webvtt-cue-writing-direction-12">writing
+direction</a>. For horizontal cues, this is the vertical offset from the top of the video viewport,
+for vertical cues, it’s the horizontal offset. The offset is for the <a data-link-type="dfn" href="#webvtt-cue-line-start-alignment" id="ref-for-webvtt-cue-line-start-alignment-2">start</a>, <a data-link-type="dfn" href="#webvtt-cue-line-center-alignment" id="ref-for-webvtt-cue-line-center-alignment-1">center</a>, or <a data-link-type="dfn" href="#webvtt-cue-line-end-alignment" id="ref-for-webvtt-cue-line-end-alignment-1">end</a> of the cue box, depending on the <a data-link-type="dfn" href="#webvtt-cue-line-alignment" id="ref-for-webvtt-cue-line-alignment-5">WebVTT cue line alignment</a> value - <a data-link-type="dfn" href="#webvtt-cue-line-start-alignment" id="ref-for-webvtt-cue-line-start-alignment-3">start</a> by default. The offset can be given either as a
+percentage of the video dimension or as a line number. Line numbers are based on the size of the
+first line of the cue. Positive line numbers count from the start of the video viewport (the first
+line is numbered 0), negative line numbers from the end of the viewport (the last line is numbered
+−1).</p>
    <p>A <dfn class="dfn-paneled" data-dfn-type="dfn" data-noexport="" id="webvtt-position-cue-setting">WebVTT position cue setting</dfn> consists of the following components, in the order
 given:</p>
    <ol>