Updated doc for troubleshooting virtual tables, particularly when using MS SQL Server data sources in Web Apps and including the new DB_ODATATRACE environment variable / registry setting introduced in the forthcoming v5.3 release.

Virtual Tables - Further Configuration and Troubleshooting

See also Additional Registry Entries and Environment Variables for more on DB_ODBCTRACE and other environment variables / registry entries that can be set to help developers to debug and optimize their Web Apps. Includes a link to the Microsoft documentation for how to safely modify the registry.