Customizing the SchemaChapter 3 How to Design the Schema 51However, if you extend the schema and find you do not use the new elements, feelfree to delete the elements you don’t use. Before removing the object classdefinitions from the schema, you need to modify each entry using the object class.Otherwise, if you remove the definition first, you might not be able to modify theentries that use the object class afterwards. Schema checks on modified entries willalso fail unless you remove the unknown object class values from the entry.Creating Custom Schema FilesYou can create custom schema files other than the 99user.ldif file provided withDirectory Server. However, your custom schema files should not be numerically oralphabetically higher than 99user.ldif or the server could experience problems.The 99user.ldif file contains attributes with the an X-ORIGIN of 'userdefined'. If you create a schema file called 99zzz.ldif, the next time you updatethe schema using LDAP or the Directory Server Console, all of the attributes withan X-ORIGIN value of 'user defined'will be written to 99zzz.ldif. Thedirectory writes them to 99zzz.ldif because the directory uses the highestsequenced file (numerically, then alphabetically) for its internal schemamanagement. The result is two LDIF files that contain duplicate information andsome information in the 99zzz.ldif file might be erased.When naming custom schema files, name them as follows:[00-99]yourname.ldifThe directory loads these schema files in numerical order, followed by alphabeticalorder. For this reason, you should use a number scheme that is higher than anydirectory standard schema defined. For example, example.com Corporationcreates a new schema file named 60examplecorp.ldif. If you name your schemafile something lower than the standard schema files, the server may encountererrors when loading the schema. In addition, all standard attributes and objectclasses will be loaded only after your custom schema elements have been loaded.You should not use 'user defined' in the X-ORIGIN field of your custom schemafiles as 'user defined' is used internally by the directory when schema is addedover LDAP. Use something more descriptive, such as 'example.com Corporationdefined'.After you have created custom schema files, you can either:• Manually copy these custom schema files to all of your servers, which requiresa restart of each server.
