A list of all Oracle database keywords can be obtained by executing following query:
SELECT * FROM v$reserved_words order by 1;
and reserved keywords can be found by
SELECT * FROM v$reserved_words where reserved='Y';
In Oracle Apps, you should not create a DFF Segment Name with any of the reserved words, however Window Prompt Name can be a reserved keyword.
SELECT f1.descriptive_flexfield_name dff_name,
descriptive_flex_context_code dff_context,
end_user_column_name dff_segment_name,
application_column_name dff_column, form_left_prompt
FROM apps.fnd_descr_flex_col_usage_vl f1, applsys.fnd_descriptive_flexs f2
WHERE f2.concatenated_segs_view_name = '&DFF_VIEW_NAME'
AND f1.application_id = f2.application_id
AND f1.descriptive_flexfield_name = f2.descriptive_flexfield_name
AND f1.enabled_flag = 'Y'
AND EXISTS (SELECT 'x'
FROM v$reserved_words rw
WHERE rw.keyword = UPPER (f1.end_user_column_name))