DatabaseMetaData.getExtraNameCharacters

Hi all,
We are developing a very simple application that permits users to define
their own tables.
We would like to leave the user the freedom to use any characters for
table and field identifiers.

We tried using accented letters, like è or ò, and it works. Then we saw
the method java.sql.DatabaseMetaData.getExtraNameCharacters() and we
thought about verifing our identifiers against this method.

The problem is that getExtraNameCharacters() returns an empty string, at
least using a 7.4 jdbc driver.

Is this the right behaviour? (I mean: should we refrain to use "strange"
letters?)

Thanks a lot,
Giuseppe