A method and data structure for storing application object type data in a repository are provided. Techniques are provided to allow users to store data for a number of custom attributes of application object types in repository tables without adding any new columns to the existing repository tables. According to one technique, data for all custom attributes of the same data type, regardless of the object type they belong to, is stored in the same table. Techniques are also provided to allow users to store data for a number of custom object types without adding any new tables to the repository. According to one technique, information identifying the attributes of a custom object type is stored in a catalog table, and the data for the attributes is stored in tables corresponding to the attributes' data types. Techniques are further provided that allow retrieval of data for custom object types and custom attributes stored in the repository tables.