Table/column annotations are supported in DBMS_METADATA, at least in the DDL transform. However, it looks like they are entirely missing in the output of the SXML transform.
Which means they won't be there either after applying the SXMLDDL transform… :-(
The following query on DBMS_METADATA_TRANSFORM_PARAMS suggests that support could be limited to the DDL transform at the time being.
select object_type, transform, param, datatype, default_val, description
from dbms_metadata_transform_params
where param like '%ANNOTATION%'
order by transform, object_type, param;
OBJECT_TYPE TRANSFORM PARAM DATATYPE DEFAULT_VAL DESCRIPTION
____________________ ____________ ______________ ___________ ______________ ______________________________________
CONSTRAINT DDL ANNOTATIONS BOOLEAN TRUE Include ANNOTATION in generated DDL
INDEX DDL ANNOTATIONS BOOLEAN TRUE Include ANNOTATION in generated DDL
MATERIALIZED_VIEW DDL ANNOTATIONS BOOLEAN TRUE Include ANNOTATION in generated DDL
SQL_DOMAIN DDL ANNOTATIONS BOOLEAN TRUE Include ANNOTATION in generated DDL
TABLE DDL ANNOTATIONS BOOLEAN TRUE Include ANNOTATION in generated DDL
VIEW DDL ANNOTATIONS BOOLEAN TRUE Include ANNOTATION in generated DDL
Adding support for annotations in the SXML and SXMLDDL transforms would be nice.
Thanks & Regards,