If I have my own DBMS and am developing to ODBC software interface, what would I be working on?
I did not exactly understand this from the Wikipedia page.
In general, ODBC is the "catchall" driver, meant to work with a wide variety of databases at a basic (lowest common denominator) level. A wide variety of software contains ODBC drivers, so supporting ODBC means providing support for a wide variety of software.
In actual practice, it is more common now to use native drivers for Oracle, SQL Server, etc. ODBC is generally used only when there is no other alternative available.
If you're developing a DBMS I would expect that 'developing to ODBC software interface' means you're creating an ODBC driver. That driver allows applications to query your database, even if they don't know about your particular DBMS. If you like applications such as Excel to use your DBMS, provide an ODBC driver.
I suppose your DBMS could act as a "client" and use another DBMS' ODBC interface to get data or schema information, that doesn't sound like a typical DBMS feature.
The Microsoft link in the Wikipedia article is a bit clearer in my opinion, MSDN has details in you're really interested in developing a driver or a client.