diff --git a/techniques/failures/F13.html b/techniques/failures/F13.html
index b913c1aa62..957ea9cf9e 100644
--- a/techniques/failures/F13.html
+++ b/techniques/failures/F13.html
@@ -1,11 +1,13 @@
 <!DOCTYPE html>
 <html lang="en">
 <head>
-   <title>Failure of Success Criterion 1.1.1 and 1.4.1 due to having a text alternative that does not include information that is conveyed by color differences in the image</title>
+   <title>Failure of Success Criterion 1.1.1 and 1.3.3 due to having a text alternative that provides information
+      relying on color differences only</title>
    <link rel="stylesheet" type="text/css" href="../../css/sources.css" class="remove">
 </head>
 <body>
-   <h1>Failure of Success Criterion 1.1.1 and 1.4.1 due to having a text alternative that does not include information that is conveyed by color differences in the image</h1>
+   <h1>Failure of Success Criterion 1.1.1 and 1.3.3 due to having a text alternative that provides information
+      relying on color differences only</h1>
    <section class="meta">
       <p class="id">ID: F13</p>
       <p class="technology">Technology: failures</p>
@@ -18,37 +20,49 @@ <h2>When to Use</h2>
    <section id="description">
       <h2>Description</h2>
       <p>The objective of this technique is to describe the failure that occurs when
-      an image uses color differences to convey information, but the text alternative for the
-      image does not convey that information. This can cause problems for people
-      who are blind, have low vision, or have color vision deficiency, because they will not be able to perceive the
-      information conveyed by the color differences.</p>
+         the text alternative for an image relies on color differences only. This can cause problems for
+         people
+         who are blind or have low vision, because they will not be able to perceive the visual cues the alternative
+         text refers to.</p>
+
+      <div class="note">
+         <div>
+            <p>Depending on its visual appearance, such an image might or might not fail Success Criterion <a href="../../Understanding/use-of-color">1.4.1 Use of Color</a>. For example, bar charts, such as the one described in the following section, can provide information based on color alone (which represents a failure) or using a combination of color and pattern for their bars (which is a pass). Please remember that 1.4.1 Use of Color addresses the needs of sighted users, who are able to perceive images and don't usually rely on text alternatives.</p>
+         </div>
+      </div>
    </section>
    <section id="examples">
       <h2>Examples</h2>
       <ul>
          <li>A bar chart of sales data is provided as an image. The chart includes
-         yearly sales figures for four employees in the Sales Department. The
-         text alternative for the image says, "The following bar chart
-         displays the yearly sales figures for the Sales Department. Mary
-         sold 3.1 Million; Fred, 2.6 Million; Bob, 2.2 Million; and Andrew,
-         3.4 Million. The red bars indicate sales that were below the yearly
-         quota". This text alternative fails to provide the information which
-         is conveyed by the color red in the image. The alternative should
-         indicate which people did not meet the sales quota rather than
-         relying on color.</li>
+            yearly sales figures for four employees in the Sales Department. The
+            text alternative for the image says: "Bar chart
+            showing the yearly sales figures for the Sales Department. Mary
+            sold 3.1 Million; Fred, 2.6 Million; Bob, 2.2 Million; and Andrew,
+            3.4 Million. The red bars indicate sales that were below the yearly
+            quota". Information about the employees not meeting the yearly quota is not provided anywhere else on the
+            page.<!-- making the bar chart image the only source of information. This accounts for a scenario in which a full-data table other kind of content (in text form) is provided below the bar chart, in which case the alternative text for the image would not rely on colour differences only --> This alternative fails to provide all the relevant information,
+            since blind users cannot perceive the bars of the chart, nor their color. The text alternative should
+            indicate which people did not meet the sales quota rather than
+            referencing the visual appearance of the image.</li>
       </ul>
    </section>
    <section id="tests">
       <h2>Tests</h2>
-      <section class="procedure"><h3>Procedure</h3>
-         <p>For all images in the content that convey information by way of color differences: </p>
+      <section class="procedure">
+         <h3>Procedure</h3>
+         <p>For all images in the content that convey information by way of color differences:</p>
          <ol>
-            <li>Check that the information conveyed by color differences is not included in the text alternative for the image.</li>
+            <li>Check that the information provided in the text alternative relies solely on color differences.</li>
+            <li>Check that the same information is not provided anywhere else on the page in
+               a way that does not rely solely on color differences.</li>
          </ol>
       </section>
-      <section class="results"><h3>Expected Results</h3>
+      <section class="results">
+         <h3>Expected Results</h3>
          <ul>
-            <li>If check #1 is true, then this failure condition applies and content fails the Success Criterion.</li>
+            <li>If check #1 and #2 are true, then this failure condition applies and content fails the Success
+               Criterion.</li>
          </ul>
       </section>
    </section>
diff --git a/understanding/understanding.11tydata.js b/understanding/understanding.11tydata.js
index fe0b0f974c..11ff2b486e 100644
--- a/understanding/understanding.11tydata.js
+++ b/understanding/understanding.11tydata.js
@@ -320,7 +320,7 @@ export default function (data) {
       "sensory-characteristics": {
         // 1.3.3
         sufficient: ["G96"],
-        failure: ["F14", "F26"],
+        failure: ["F13", "F14", "F26"],
       },
 
       orientation: {
@@ -363,7 +363,7 @@ export default function (data) {
           },
         ],
         advisory: ["C15"],
-        failure: ["F13", "F73", "F81"],
+        failure: ["F73", "F81"],
       },
 
       "audio-control": {
