The meta:class directive allows you to ascribe special meaning to a relationship which Xataface can use in various parts of your application to provide enhanced capabilities.
For example you can specify a relationship as a "parent" relationship, thereby using the relationship to obtain the "parent" of records of this table. This can be used to help build breadcrumbs.
You can also specify a relationship as a "children" relationship which would treat records in the relationship as children of the current record. This can be used in conjunction with the list:type=treetable directive of the relationships.ini file to build a tree table that navigates all child records and subtrees.
The Dataface_Record class contains some methods for retrieving the parent and children of records and these methods will take into account any settings you make here.
Designates the relationship as a 'parent' relationship, meaning that the first record in this relationship will be treated as the parent of the current record. This setting can be overridden by the getParent? method of the table delegate class if implemented.
Designates the relationship as a 'children' relationship meaning that records of the the relationship will be treated as a children. This setting can be overridden by the getChildren method of the table delegate class if implemented.