Application data, model elements and sometimes their attributes can be assigned optional metadata attributes, to define application-specific behavior. If these are attributes are not specifically defined when creating an element, they are simply not available.
The attributes are available under the "meta" sub attribute: for example, if the 'locked' attribute has been defined for an object called 'my_object', it can be referenced by my_object.meta.locked.
Metadata is application-specific and custom metadata attributes can be defined by an application for specific purposes.
When defined, the locked meta attribute can control the persistency of a persistent model element (parameter, curve, surface, property...): if set to true, the associated object is ignored when loading presets. When set to 'always', the generated locked attribute is read only. When set to 'never', no lock attribute is generated.
The value of the locked meta attribute can be changed at runtime. The value defined in the element is the default value.
<!-- Define a parameter with a locked meta attribute, disabled by default. The locked meta attribute can be referenced using my_param.meta.locked --> <PARAM id="my_param" min="0" max="10" locked="false"/>