Please point me to any reference materials from which I may learn about the rules / restrictions of naming fields, tables or databases.

For example, are spaces allowed ?
Or the under-score character .... _
Is it OK to name a field DATE or TIME ?

I'm asking because I've been trying to use SQLMaestro's "Data Wizard" to convert some Microsoft 2003 databases into FireBird and the application is erroring out and the error has not, as yet, brought me any closer to an answer ( why is it that some error messages from applications are so general and/or vague ? )

I'm wondering if the application is erroring out due to poor naming conventions on the part of the person who designed the database / tables / fields.

Thank you in advance for your assistance.