> For the complete documentation index, see [llms.txt](https://docs.helmut.de/helmut4-releases/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.helmut.de/helmut4-releases/v4.7.0/helmut4-components/helmutco/metadata/custom-metadata.md).

# Custom Metadata

This page is about valid key-value pairs which can be used within Adobe Premiere Pro + Media Encoder and synced to Cosmo.

In general [Adobe is following](https://www.adobe.com/products/xmp.html) the default definition of allowed character for [xmp](https://www.loc.gov/standards/mets/mets-home.html).

### Key

* **Are** case-sensitive
* Can **not** start with a number
* Can **not** contain underscore (\_)

### Value

* **Are** case-sensitive
* **Can** start with a number, contain only numbers, or be a combination of numbers and letters
* **Can** contain underscores (\_)

#### Example for metadata key

Metadata key: "*key\_value pair"*\
\
This is **not** valid because there is a underscore in the key name. While values can contain spaces, keys can not.<br>

Metadata key: "*1story"*\
\
This is **not** valid because the key starts with a number which is forbidden.

### **Disallowed characters in keys or values**

The following characters are reserved and not allowed in key names or values.

<table><thead><tr><th width="167">Character</th><th>not allowed in</th><th>Description</th></tr></thead><tbody><tr><td>"</td><td>Key</td><td>Double quotes</td></tr><tr><td>'</td><td>Key</td><td>Single quotes or apostrophe</td></tr><tr><td>=</td><td>Key/Value</td><td>Equal sign</td></tr><tr><td>!</td><td>Key</td><td>Exclamation point</td></tr><tr><td>+</td><td>Key</td><td>Plus sign</td></tr><tr><td>#</td><td>Key/Value</td><td>Pound or hash symbol</td></tr><tr><td>*</td><td>Key/Value</td><td>Asterisk</td></tr><tr><td>~</td><td>Key/Value</td><td>Tilde</td></tr><tr><td>;</td><td>Key/Value</td><td>Semicolon</td></tr><tr><td>^</td><td>Key/Value</td><td>Caret</td></tr><tr><td>()</td><td>Key/Value</td><td>Parentheses</td></tr><tr><td>&#x3C; ></td><td>Key/Value</td><td>Angle brackets</td></tr><tr><td>[ ]</td><td>Key/Value</td><td>Square brackets</td></tr><tr><td>,</td><td>Key/Value</td><td>Comma</td></tr><tr><td>&#x26;</td><td>Key/Value</td><td>Ampersand</td></tr><tr><td>|</td><td>Key/Value</td><td>Pipe</td></tr><tr><td>?</td><td>Key</td><td>Question mark</td></tr><tr><td>:</td><td>Key/Value</td><td>Double point</td></tr></tbody></table>

### Umlauts

As umlauts are often treated as special characters, those can cause issues when working on different operating systems as well with foreign language projects.

Within Helmut4 we have defined the most known and used umlauts in the European region to be proper detected & escaped when indexing a project.

| Lower case | Uper case | Description     |
| ---------- | --------- | --------------- |
| ä          | Ä         | German          |
| ö          | Ö         | German          |
| ü          | Ü         | German          |
| ß          | ẞ         | German          |
| æ          | Æ         | Northern Europe |
| ø          | Ø         | Northern Europe |
| å          | Å         | Northern Europe |
| -          | À         | Western Europe  |
| â          | Â         | Western Europe  |
| ç          | Ç         | Western Europe  |
| è          | È         | Western Europe  |
| é          | É         | Western Europe  |
| ê          | Ê         | Western Europe  |
| ë          | Ë         | Western Europe  |
| î          | Î         | Western Europe  |
| ô          | Ô         | Western Europe  |
| œ          | Œ         | Western Europe  |
| ù          | Ù         | Western Europe  |
| -          | Ÿ         | Western Europe  |
| ì          | -         | Western Europe  |
| ó          | -         | Western Europe  |
| ó          | -         | Western Europe  |
| õ          | -         | Western Europe  |
| ò          | -         | Western Europe  |
| ú          | -         | Western Europe  |