Substitution Syntax Extension

The X-SUBST attribute syntax extension can be used to define new string syntaxes with values in terms of existing syntaxes. It is provided for use when extending the native directory server schema with a non-standard schema (or an external schema) that uses syntaxes not supported by OpenDS. Instead of altering the imported schema, extend it with the X-SUBST extension to instruct the directory server to treat values in terms of a supported syntax.

The following example defines a new syntax, AttCertPath, in terms of an existing syntax, 1.3.6.1.4.1.1466.115.121.1.15, directory string. This change must be made under cn=schema.

$ ldapmodify -p 1389 -h localhost -D "cn=Directory Manager" -w password
dn: cn=schema
objectClass: top
objectClass: ldapSubentry
objectClass: subschema
ldapSyntaxes: ( 1.3.6.1.4.1.4203.666.11.10.2.4
  DESC 'AttCertPath'
  X-SUBST '1.3.6.1.4.1.1466.115.121.1.15' )

This feature can be useful during migration and can lessen the impact on the schema. For example, during migration to OpenDS, an incoming schema can contain attribute definitions that use an undefined syntax. The X-SUBST attribute syntax extension provides a means to define those missing syntaxes in terms of other, more general syntaxes. With this capability, the schema and data can be migrated without the need to modify the schema or data or to implement new syntaxes.