Ad-hoc queries: work with the data base directly via data manipulation language, i.e. SQL.

The result is an HTML document:

1. Fill-out form for a SQL command:SELECT

2. Fill-out form for any SQL command:free SQL query

The result can be seen in both HTML and VRML documents:

1 Fill-out form to visualize body and surface objects: SELECT + visualize

Embedded queries: work with the data base via a high-level programming language, i.e. Perl with embedded SQL statements.

1. "Find buildings which have one or more common points "

2. "Find buildings with common walls "

3. "Find buildings along streets" (there is not appropriate data yet!)

4. "Visibility check"