Reported by Dmitry:

I see a very weird situation. A database and connection charsets are win1251, database is empty and it's in ODS11.1:

CREATE PROCEDURE P (
  P_TABLENAME VARCHAR(30) ,
  P_IDNAME VARCHAR(30) ,
  P_SEQNAME VARCHAR(30) ,
  P_ISUSEFUNC SMALLINT
)
RETURNS (
  COLUMN_VALUE BIGINT
)
AS
declare variable l_MaxId bigint;
begin
  /*
  -- Находим разрыв в значениях ПК таблицы
  -- если разрыв отсутствует то дергаем секвенс
  -- p_IsUseFunc=1 - дергать секвенс ч/з ф-цию GetSeqValue
  */
end

The text is in cp1251 too.

Now, if I query:

SELECT PR.rdb$procedure_name
FROM RDB$PROCEDURES PR
WHERE PR.RDB$PROCEDURE_SOURCE containing '1'
and PR.rdb$procedure_name='P'

I get the error "cannot transliterate". If I remove at least one of the hyphens, the query succeeds. But a removal of any other character doesn't help.

It looks like a bug, but with very unusual symptoms.