# Tags

Each copy of an object also maintains a set of tags associated with it. Tags are strings of nonzero length and can be associated to objects to help organize them or annotate them.

Tags are returned by the `describe` method, and modified by the `addTags` and `removeTags` methods.

## API method: `/class-xxxx/addTags`

### Specification

Adds the specified tags to the object in the specified project. If any of the tags are already present, no action is taken for those tags.

### Inputs

* `project` **string** (required) ID of the project or container containing the object to be modified.
* `tags` **array of strings** (required) Tags to be added.

### Outputs

* `id` **string** ID of the manipulated object.

### Errors

* InvalidInput (the input is not a hash, `project` is missing or is not a string, the key `tags` is missing, or its value is not an array, or the array contains at least one invalid (not a string of nonzero length) tag)
* ResourceNotFound (the specified object does not exist, the specified project does not exist, or the specified project does not contain the specified object)
* PermissionDenied (If the object is open, UPLOAD access is required, otherwise CONTRIBUTE access is required for the specified project)

## API method: `/class-xxxx/removeTags`

### Specification

Removes the specified tags from the object in the specified project. Ensures that the specified tags are not part of the object -- if any of the tags are already missing, no action is taken for those tags.

### Inputs

* `project` **string** (required) ID of the project or container containing the object to be modified.
* `tags` **array of strings** (required) Tags to be removed.

### Outputs

* `id` **string** ID of the manipulated object.

### Errors

* InvalidInput (the input is not a hash, `project` is missing or is not a string, or the key `tags` is missing, or its value is not an array, or the array contains at least one invalid (not a string of nonzero length) tag)
* ResourceNotFound (the specified object does not exist, the specified project does not exist, or the specified project does not contain the specified object)
* PermissionDenied (If the object is open, UPLOAD access is required, otherwise CONTRIBUTE access is required for the specified project)