Thanks! I'll save this talk as a reference.
Really my question was focused on possibile risks or safety issues; it's so
strange that a database (since I see wikisource as a database) is mainly
indexed, from the user's point of view, on a variable field as title of the
page, that I suspected some serious safety issue. And - strangely enough -
id is not shown at all into pages, nor there's any magic word or other user
friendly method to get it.
From a practical point of view, many from wikisource
page titles are very
long, often they use non-ascii characters and mixtures of
not capitalized characters, they can't be used as they are as local file
names... in brief, I feel all this stuff almost as annoying as the
apostophes used in wiki markup for bold and italic. ;-)