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settings_template.toml

 [data]
 # Specify here where the data is.
 # All data paths should be relative to data_root and
-# data_root must be either an absolute path or an S3 bucket URL
+# data_root must be either an absolute filesystem path or an S3 bucket URL
 data_root = ""
 table_path = ""
+# For images in an S3 bucket, images_root must be empty
+# because the bucket represents the image root directory
 images_root = ""
 
 [columns]