Please, see flag parameter description in UDM_ISPELL_TYPE_DB.
UDM_ISPELL_TYPE_SPELL - indicates that ispell data should be loaded from file and initiates loading of ispell dictionary file. In this case val1 defines double letter language code for which affixes are loaded, and val2 - file path. Please note, that if a relative path entered, the module looks for the file not in UDM_CONF_DIR, but in relation to current path, i.e. to the path where the script is executed. In case of error in this mode, e.g. if file is absent, the function will return FALSE, and an error message will be displayed. Error message text cannot be accessed through udm_error() and udm_errno(), since those functions can only return messages associated with SQL. Please, see flag parameter description in UDM_ISPELL_TYPE_DB.