# Functional concepts

**Characteristics in configuring** **eXtended Metadata**

There are two general areas in which LIBSAFE needs to be configured to manage extended metadata. On the one hand a user with access to the system configuration can build the classes and types of metadata that the environment will use; on the other hand, a user who can access an object's catalog can create the sets and blocks.

**LIBSAFE extended metadata structure**

In LIBSAFE an extended metadata block is conditioned by:

* The metadata Class

There are two metadata classes: Structured or Free.

**Structured** are based on a format and a language called (LXM) to delimit and adapt the data and values of each (For more information about this implementation with LXM code, please refer to the LXM guide in LIBSAFE).

**Free** are the classes that allow to contain any kind of information independent of an ordered schema.

* The metadata Type

From the class that is selected, the type complements and specializes the class with more information about the block. **Structured** types contain a schema code (LXM), a start tag and the possibility of using an XSLT stylesheet to post-process the block data and present it in a specific way. In the case of **Free** types, the information is complemented, indicating whether the content is JSON format, XML (tagged information interchange formats) or Free (Text without any definition or structure, e.g. a paragraph of text).

* The metadata Sets

These are containers of several metadata blocks of the same type; they are created from the catalog of an object and the user does not need access to the system configuration panel. Sets require a name, description and a class. By default the sets that are created through the web interface are created for the entire contents of the object, but they can also be relative only to files, which are automatically generated by LIBSAFE.

* The data Blocks

Blocks are the content itself as a resultant of the pre-processing, post-processing or the direct creation of content from the user interface.
