# Tagging in Neptune using the API
<a name="tagging-api"></a>

You can add, list, or remove tags for a DB instance using the Neptune API.
+ To add a tag to a Neptune resource, use the [`AddTagsToResource`](API_AddTagsToResource.html) operation.
+ To list tags that are assigned to a Neptune resource, use the [`ListTagsForResource`](API_ListTagsForResource.html).
+ To remove tags from a Neptune resource, use the [`RemoveTagsFromResource`](API_RemoveTagsFromResource.html) operation.

To learn more about how to construct the required ARN, see [Constructing an ARN for Neptune](tagging-arns-constructing.md).

When working with XML using the Neptune API, tags use the following schema:

```
 1. <Tagging>
 2.     <TagSet>
 3.         <Tag>
 4.             <Key>Project</Key>
 5.             <Value>Trinity</Value>
 6.         </Tag>
 7.         <Tag>
 8.             <Key>User</Key>
 9.             <Value>Jones</Value>
10.         </Tag>
11.     </TagSet>
12. </Tagging>
```

The following table provides a list of the allowed XML tags and their characteristics. Values for `Key` and `Value` are case-dependent. For example, `project=Trinity` and `PROJECT=Trinity` are two distinct tags. 



| Tagging Element | Description | 
| --- | --- | 
| TagSet | A tag set is a container for all tags that are assigned to a Neptune resource. There can be only one tag set per resource. You work with a TagSet only through the Neptune API. | 
| Tag | A tag is a user-defined key-value pair. There can be from 1 to 50 tags in a tag set. | 
| Key | A key is the required name of the tag. The string value can be from 1 to 128 Unicode characters in length and cannot be prefixed with "`rds:`" or "`aws:`". The string can contain only the set of Unicode letters, digits, white space, '\_', '.', '/', '=', '\+', '-' (Java regex: "`^([\\p{L}\\p{Z}\\p{N}_.:/=+\\-]*)$`").<br />Keys must be unique to a tag set. For example, you can't have a key-pair in a tag set with the key the same but with different values, such as `project/Trinity` and `project/Xanadu`.  | 
| Value | A value is the optional value of the tag. The string value can be from 1 to 256 Unicode characters in length and cannot be prefixed with "`rds:`" or "`aws:`". The string can contain only the set of Unicode letters, digits, white space, '\_', '.', '/', '=', '\+', '-' (Java regex: "`^([\\p{L}\\p{Z}\\p{N}_.:/=+\\-]*)$`").<br />Values don't have to be unique in a tag set and can be null. For example, you can have a key-value pair in a tag set of `project/Trinity` and `cost-center/Trinity`. |