DRG-50901: text query parser syntax error

Question

The query
SELECT * FROM ij
where
CONTAINS (ij.summary, 'ATTENZIONE!') > 0 returns an error:
ORA-29902: error in executing ODCIIndexStart() routine
ORA-20000: Oracle Text error:
DRG-50901: text query parser syntax error on line 1, column 13
Why?
There is a TEXT index on the summary column:
CREATE INDEX IJL_SUMMARY_IX ON IJ
(SUMMARY)
INDEXTYPE IS CTXSYS.CONTEXT
PARAMETERS('
    lexer           MITO_LEXER
    wordlist        DEFAULT_WORDLIST
    stoplist        IJL_STOPLIST
    storage         IJL_TEXT_STORAGE
    SYNC (EVERY "SYSDATE + 10/1440")')
PARALLEL ( DEGREE 4 INSTANCES 1 );where the MITO_LEXER is
BEGIN
CTX_DDL.create_preference ('mito_lexer', 'BASIC_LEXER');
CTX_DDL.set_attribute ('mito_lexer', 'INDEX_STEMS', 'ITALIAN');
-- MITO-318: search on Text Index for Asterisks
CTX_DDL.set_attribute ('mito_lexer', 'printjoins', '*');
END;
/

Answer 1

Because the exclamation mark ("!") is a reserved operator, meaning soundex, and must appear before the word it applies to.