diff --git a/.phpstorm.meta.php b/.phpstorm.meta.php
index 9ee787aeb1..c6f91325ee 100644
--- a/.phpstorm.meta.php
+++ b/.phpstorm.meta.php
@@ -27,7 +27,7 @@
     expectedArguments(\League\CommonMark\Inline\Element\Newline::__construct(), 0, argumentsSet('league_commonmark_newline_types'));
     expectedReturnValues(\League\CommonMark\Inline\Element\Newline::getType(), argumentsSet('league_commonmark_newline_types'));
 
-    registerArgumentsSet('league_commonmark_options', 'renderer', 'enable_em', 'enable_strong', 'use_asterisk', 'use_underscore', 'unordered_list_markers', 'html_input', 'allow_unsafe_links', 'max_nesting_level', 'heading_permalink', 'heading_permalink/html_class', 'heading_permalink/id_prefix', 'heading_permalink/inner_contents', 'heading_permalink/insert', 'heading_permalink/title', 'table_of_contents', 'table_of_contents/style', 'table_of_contents/normalize', 'table_of_contents/position', 'table_of_contents/html_class', 'table_of_contents/min_heading_level', 'table_of_contents/max_heading_level', 'table_of_contents/placeholder');
+    registerArgumentsSet('league_commonmark_options', 'renderer', 'enable_em', 'enable_strong', 'use_asterisk', 'use_underscore', 'unordered_list_markers', 'html_input', 'allow_unsafe_links', 'max_nesting_level', 'external_link', 'external_link/nofollow', 'external_link/noopener', 'external_link/noreferrer', 'heading_permalink', 'heading_permalink/html_class', 'heading_permalink/id_prefix', 'heading_permalink/inner_contents', 'heading_permalink/insert', 'heading_permalink/title', 'table_of_contents', 'table_of_contents/style', 'table_of_contents/normalize', 'table_of_contents/position', 'table_of_contents/html_class', 'table_of_contents/min_heading_level', 'table_of_contents/max_heading_level', 'table_of_contents/placeholder');
     expectedArguments(\League\CommonMark\EnvironmentInterface::getConfig(), 0, argumentsSet('league_commonmark_options'));
     expectedArguments(\League\CommonMark\Util\ConfigurationInterface::get(), 0, argumentsSet('league_commonmark_options'));
     expectedArguments(\League\CommonMark\Util\ConfigurationInterface::set(), 0, argumentsSet('league_commonmark_options'));
diff --git a/CHANGELOG.md b/CHANGELOG.md
index f9cc4d5e83..8bdb20ea66 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,7 @@ Updates should follow the [Keep a CHANGELOG](https://keepachangelog.com/) princi
 
  - Added the ability to render `TableOfContents` nodes anywhere in a document (given by a placeholder)
  - Added the ability to properly clone `Node` objects
+ - Added options to customize the value of `rel` attributes set via the `ExternalLink` extension (#476)
  - Added new classes:
    - `TableOfContentsGenerator`
    - `TableOfContentsGeneratorInterface`
@@ -18,6 +19,7 @@ Updates should follow the [Keep a CHANGELOG](https://keepachangelog.com/) princi
 ### Changed
 
  - "Moved" the `TableOfContents` class into a new `Node` sub-namespace (with backward-compatibility)
+ - External links detected by the `ExternalLink` extension will now include `nofollow` in the renderer `rel` attribute (#476)
 
 ### Deprecated
 
diff --git a/docs/1.5/extensions/external-links.md b/docs/1.5/extensions/external-links.md
index a8d4175d38..904aa6b725 100644
--- a/docs/1.5/extensions/external-links.md
+++ b/docs/1.5/extensions/external-links.md
@@ -9,7 +9,8 @@ redirect_from: /extensions/external-links/
 
 This extension can detect links to external sites and adjust the markup accordingly:
 
- - Adds a `rel="noopener noreferrer"` attribute
+ - Make the links open in new tabs/windows
+ - Adds a `rel` attribute to the resulting `<a>` tag with values like `"nofollow noopener noreferrer"`
  - Optionally adds any custom HTML classes
 
 ## Usage
@@ -30,9 +31,12 @@ $environment->addExtension(new ExternalLinkExtension());
 // Set your configuration
 $config = [
     'external_link' => [
-        'internal_hosts' => 'www.example.com', // Don't forget to set this!
+        'internal_hosts' => 'www.example.com', // TODO: Don't forget to set this!
         'open_in_new_window' => true,
         'html_class' => 'external-link',
+        'nofollow' => 'external',
+        'noopener' => 'all',
+        'noreferrer' => 'external',
     ],
 ];
 
@@ -73,6 +77,15 @@ This option (which defaults to `false`) determines whether any external links sh
 
 This option allows you to provide a `string` containing one or more HTML classes that should be added to the external link `<a>` tags:  No classes are added by default.
 
+### `nofollow`, `noopener`, and `noreferrer`
+
+These options allow you to configure whether a `rel` attribute should be applied to links.  Each of these options can be set to one of the following `string` values:
+
+ - `'external'` - **Apply to external links only (default)**
+ - `'internal'` - Apply to internal links only
+ - `'all'` - Apply to all links (both internal and external)
+ - `''` (empty string) - Don't apply to any links
+
 ## Advanced Rendering
 
 When an external link is detected, the `ExternalLinkProcessor` will set the `external` data option on the `Link` node to either `true` or `false`.  You can therefore create a [custom link renderer](/1.5/customization/inline-rendering/) which checks this value and behaves accordingly:
diff --git a/src/Extension/ExternalLink/ExternalLinkProcessor.php b/src/Extension/ExternalLink/ExternalLinkProcessor.php
index 5a2f66481b..decff4ccf6 100644
--- a/src/Extension/ExternalLink/ExternalLinkProcessor.php
+++ b/src/Extension/ExternalLink/ExternalLinkProcessor.php
@@ -17,6 +17,11 @@
 
 final class ExternalLinkProcessor
 {
+    public const APPLY_NONE = '';
+    public const APPLY_ALL = 'all';
+    public const APPLY_EXTERNAL = 'external';
+    public const APPLY_INTERNAL = 'internal';
+
     /** @var EnvironmentInterface */
     private $environment;
 
@@ -50,6 +55,7 @@ public function __invoke(DocumentParsedEvent $e)
 
                 if (self::hostMatches($host, $internalHosts)) {
                     $link->data['external'] = false;
+                    $this->applyRelAttribute($link, false);
                     continue;
                 }
 
@@ -63,7 +69,7 @@ private function markLinkAsExternal(Link $link, bool $openInNewWindow, string $c
     {
         $link->data['external'] = true;
         $link->data['attributes'] = $link->getData('attributes', []);
-        $link->data['attributes']['rel'] = 'noopener noreferrer';
+        $this->applyRelAttribute($link, true);
 
         if ($openInNewWindow) {
             $link->data['attributes']['target'] = '_blank';
@@ -74,6 +80,27 @@ private function markLinkAsExternal(Link $link, bool $openInNewWindow, string $c
         }
     }
 
+    private function applyRelAttribute(Link $link, bool $isExternal): void
+    {
+        $rel = [];
+
+        foreach (['nofollow', 'noopener', 'noreferrer'] as $type) {
+            $option = $this->environment->getConfig('external_link/' . $type, self::APPLY_EXTERNAL);
+            switch (true) {
+                case $option === self::APPLY_ALL:
+                case $isExternal && $option === self::APPLY_EXTERNAL:
+                case !$isExternal && $option === self::APPLY_INTERNAL:
+                    $rel[] = $type;
+            }
+        }
+
+        if ($rel === []) {
+            return;
+        }
+
+        $link->data['attributes']['rel'] = \implode(' ', $rel);
+    }
+
     /**
      * @param string $host
      * @param mixed  $compareTo
diff --git a/tests/unit/Extension/ExternalLink/ExternalLinkProcessorTest.php b/tests/unit/Extension/ExternalLink/ExternalLinkProcessorTest.php
index d5e45cb62d..f04784f51a 100644
--- a/tests/unit/Extension/ExternalLink/ExternalLinkProcessorTest.php
+++ b/tests/unit/Extension/ExternalLink/ExternalLinkProcessorTest.php
@@ -23,14 +23,14 @@ final class ExternalLinkProcessorTest extends TestCase
 
     public function testDefaultConfiguration()
     {
-        $expected = '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>' . "\n";
+        $expected = '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>';
 
         $this->assertEquals($expected, $this->parse(self::INPUT));
     }
 
     public function testCustomConfiguration()
     {
-        $expected = '<p>My favorite sites are <a rel="noopener noreferrer" target="_blank" class="external-link" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>' . "\n";
+        $expected = '<p>My favorite sites are <a rel="nofollow noopener noreferrer" target="_blank" class="external-link" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>';
 
         $config = [
             'external_link' => [
@@ -47,7 +47,7 @@ public function testWithBadUrls()
     {
         $input = 'Report [xss](javascript:alert(0);) vulnerabilities by emailing <colinodell@gmail.com>';
 
-        $expected = '<p>Report <a href="javascript:alert(0);">xss</a> vulnerabilities by emailing <a href="mailto:colinodell@gmail.com">colinodell@gmail.com</a></p>' . "\n";
+        $expected = '<p>Report <a href="javascript:alert(0);">xss</a> vulnerabilities by emailing <a href="mailto:colinodell@gmail.com">colinodell@gmail.com</a></p>';
 
         $this->assertEquals($expected, $this->parse($input));
     }
@@ -59,7 +59,7 @@ private function parse(string $markdown, array $config = [])
 
         $c = new CommonMarkConverter($config, $e);
 
-        return $c->convertToHtml($markdown);
+        return \rtrim($c->convertToHtml($markdown));
     }
 
     /**
@@ -91,4 +91,94 @@ public function dataProviderForTestHostMatches()
         // You can even mix-and-match multiple strings with multiple regexes
         yield ['www.colinodell.com', ['/colinodell\.com/', 'aol.com'], true];
     }
+
+    /**
+     * @param string $nofollow
+     * @param string $noopener
+     * @param string $noreferrer
+     * @param string $expectedOutput
+     *
+     * @dataProvider dataProviderForTestRelOptions
+     */
+    public function testRelOptions(string $nofollow, string $noopener, string $noreferrer, string $expectedOutput): void
+    {
+        $config = [
+            'external_link' => [
+                'nofollow' => $nofollow,
+                'noopener' => $noopener,
+                'noreferrer' => $noreferrer,
+                'internal_hosts' => ['commonmark.thephpleague.com'],
+            ],
+        ];
+
+        $this->assertEquals($expectedOutput, $this->parse(self::INPUT, $config));
+    }
+
+    public function dataProviderForTestRelOptions(): iterable
+    {
+        yield ['',         '',         '',         '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         '',         'all',      '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         '',         'external', '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         '',         'internal', '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'all',      '',         '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'all',      'all',      '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'all',      'external', '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'all',      'internal', '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'external', '',         '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'external', 'all',      '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'external', 'external', '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'external', 'internal', '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'internal', '',         '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'internal', 'all',      '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'internal', 'external', '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['',         'internal', 'internal', '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      '',         '',         '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      '',         'all',      '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      '',         'external', '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      '',         'internal', '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'all',      '',         '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'all',      'all',      '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'all',      'external', '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'all',      'internal', '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'external', '',         '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'external', 'all',      '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'external', 'external', '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'external', 'internal', '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'internal', '',         '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'internal', 'all',      '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'internal', 'external', '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['all',      'internal', 'internal', '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', '',         '',         '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', '',         'all',      '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', '',         'external', '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', '',         'internal', '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'all',      '',         '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'all',      'all',      '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'all',      'external', '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'all',      'internal', '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'external', '',         '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'external', 'all',      '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'external', 'external', '<p>My favorite sites are <a rel="nofollow noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'external', 'internal', '<p>My favorite sites are <a rel="nofollow noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'internal', '',         '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'internal', 'all',      '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'internal', 'external', '<p>My favorite sites are <a rel="nofollow noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['external', 'internal', 'internal', '<p>My favorite sites are <a rel="nofollow" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', '',         '',         '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', '',         'all',      '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', '',         'external', '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', '',         'internal', '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'all',      '',         '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'all',      'all',      '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'all',      'external', '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'all',      'internal', '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'external', '',         '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'external', 'all',      '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'external', 'external', '<p>My favorite sites are <a rel="noopener noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'external', 'internal', '<p>My favorite sites are <a rel="noopener" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'internal', '',         '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'internal', 'all',      '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'internal', 'external', '<p>My favorite sites are <a rel="noreferrer" href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+        yield ['internal', 'internal', 'internal', '<p>My favorite sites are <a href="https://www.colinodell.com">https://www.colinodell.com</a> and <a rel="nofollow noopener noreferrer" href="https://commonmark.thephpleague.com">https://commonmark.thephpleague.com</a></p>'];
+    }
 }