If the LOB data is less than 512 bytes it will always be stored directly.
fbsql_set_lob_mode() sets the mode for retrieving LOB data from the database. When BLOB and CLOB data is stored in FrontBase it can be stored direct or indirect. Direct stored LOB data will always be fetched no matter the setting of the lob mode. If the LOB data is less than 512 bytes it will always be stored directly.