stefan.rickfjord@g... wrote:
> Hi,
> 
> I am a newbie to programming using XML and I'm currently working on a
> side-project which will house some database information in a XML-file.
> I am writing a DTD to specify the XML-format, mostly for the purpose of
> documenting the XML database.
> 
> My issue is that I have some fields, e.g.
> <!ELEMENT Vehicle ( Car? )>
> <!ELEMENT Car ( Gasoline | Diesel )>
> <!ELEMENT Gasoline EMPTY>
> <!ELEMENT Diesel EMPTY>
> 
> but I want to make sure that this database is extendable. I.e. after
> using the database for a while in my application I want to be able to
> add stuff that I come up with later on, e.g.
> <!ELEMENT Motorcycle ( Sportbike | Harley )>
> <!ELEMENT Sportbike EMPTY>
> <!ELEMENT Harley EMPTY>

<!ENTITY % bikes SYSTEM "list.of.bikes">
...
<!ELEMENT Motorcycle EMPTY>
<!ATTLIST Motorcycle type (%bikes;) #REQUIRED>

where the file list.of.bikes contains something like

Sportbike|
Harley|
Triumph|
Yamaha

etc.

Now to keep the list up to date, you just have to edit list.of.bikes

///Peter
-- 
XML FAQ: http://xml.silmaril.ie/