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docs/content/en/content-management/cross-references.md

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+---
+title: Links and Cross References
+description: Hugo makes it easy to link documents together.
+date: 2017-02-01
+publishdate: 2017-02-01
+lastmod: 2017-03-31
+categories: [content management]
+keywords: ["cross references","references", "anchors", "urls"]
+menu:
+  docs:
+    parent: "content-management"
+    weight: 100
+weight: 100	#rem
+aliases: [/extras/crossreferences/]
+toc: true
+---
+
+
+ The `ref` and `relref` shortcodes link documents together, both of which are [built-in Hugo shortcodes][]. These shortcodes are also used to provide links to headings inside of your content, whether across documents or within a document. The only difference between `ref` and `relref` is whether the resulting URL is absolute (`http://1.com/about/`) or relative (`/about/`), respectively.
+
+## Use `ref` and `relref`
+
+```
+{{</* ref "document.md" */>}}
+{{</* ref "#anchor" */>}}
+{{</* ref "document.md#anchor" */>}}
+{{</* relref "document.md" */>}}
+{{</* relref "#anchor" */>}}
+{{</* relref "document.md#anchor" */>}}
+```
+
+The single parameter to `ref` is a string with a content `documentname` (e.g., `about.md`) with or without an appended in-document `anchor` (`#who`) without spaces.
+
+### Document Names
+
+The `documentname` is the name of a document, including the format extension; this may be just the filename, or the relative path from the `content/` directory. With a document `content/blog/post.md`, either format will produce the same result:
+
+```
+{{</* relref "blog/post.md" */>}} => `/blog/post/`
+{{</* relref "post.md" */>}} => `/blog/post/`
+```
+
+If you have the same filename used across multiple sections, you should only use the relative path format; otherwise, the behavior will be `undefined`. This is best illustrated with an example `content` directory:
+
+```
+.
+└── content
+    ├── events
+    │   └── my-birthday.md
+    ├── galleries
+    │   └── my-birthday.md
+    ├── meta
+    │   └── my-article.md
+    └── posts
+        └── my-birthday.md
+```
+
+To be sure to get the correct reference in this case, use the full path: 
+
+{{< code file="content/meta/my-article.md" copy="false" >}}
+{{</* relref "events/my-birthday.md" */>}} => /events/my-birthday/
+{{< /code >}}
+
+### With Multiple Output Formats
+
+If the page exists in multiple [output formats][], `ref` or `relref` can be used with a output format name:
+
+```
+ [Neat]({{</* ref "blog/neat.md" "amp" */>}})
+```
+
+### Anchors
+
+When an `anchor` is provided by itself, the current page’s unique identifier will be appended; when an `anchor` is provided appended to `documentname`, the found page's unique identifier will be appended:
+
+```
+{{</* relref "#anchors" */>}} => #anchors:9decaf7
+{{</* relref "about-hugo/hugo-features.md#content" */>}} => /blog/post/#who:badcafe
+```
+
+The above examples render as follows for this very page as well as a reference to the "Content" heading in the Hugo docs features pageyoursite
+
+```
+{{</* relref "#who" */>}} => #who:9decaf7
+{{</* relref "blog/post.md#who" */>}} => /blog/post/#who:badcafe
+```
+
+More information about document unique identifiers and headings can be found [below]({{< ref "#hugo-heading-anchors" >}}).
+
+### Examples
+
+* `{{</* ref "blog/post.md" */>}}` => `https://example.com/blog/post/`
+* `{{</* ref "post.md#tldr" */>}}` => `https://example.com/blog/post/#tldr:caffebad`
+* `{{</* relref "post.md" */>}}` => `/blog/post/`
+* `{{</* relref "blog/post.md#tldr" */>}}` => `/blog/post/#tldr:caffebad`
+* `{{</* ref "#tldr" */>}}` => `#tldr:badcaffe`
+* `{{</* relref "#tldr" */>}}` => `#tldr:badcaffe`
+
+## Hugo Heading Anchors
+
+When using Markdown document types, Hugo generates heading anchors automatically. The generated anchor for this section is `hugo-heading-anchors`. Because the heading anchors are generated automatically, Hugo takes some effort to ensure that heading anchors are unique both inside a document and across the entire site.
+
+Ensuring heading uniqueness across the site is accomplished with a unique identifier for each document based on its path. Unless a document is renamed or moved between sections *in the filesystem*, the unique identifier for the document will not change: `blog/post.md` will always have a unique identifier of `81df004c333b392d34a49fd3a91ba720`.
+
+`ref` and `relref` were added so you can make these reference links without having to know the document’s unique identifier. (The links in document tables of contents are automatically up-to-date with this value.)
+
+```
+{{</* relref "content-management/cross-references.md#hugo-heading-anchors" */>}}
+/content-management/cross-references/#hugo-heading-anchors:77cd9ea530577debf4ce0f28c8dca242
+```
+
+### Manually Specifying Anchors
+
+For Markdown content files, if the `headerIds` [Blackfriday extension][bfext] is
+enabled (which it is by default), user can manually specify the anchor for any
+heading.
+
+Few examples:
+
+```
+## Alpha 101 {#alpha}
+
+## Version 1.0 {#version-1-dot-0}
+```
+
+[built-in Hugo shortcodes]: /content-management/shortcodes/#using-the-built-in-shortcodes
+[lists]: /templates/lists/
+[output formats]: /templates/output-formats/
+[shortcode]: /content-management/shortcodes/
+[bfext]: /content-management/formats/#blackfriday-extensions