1. In-build Encryption support
2. Full Text Search
3. Boolean Search
4. C/C++, VB availability
5. Cross Platform (LINUX & MAC & WINDOWS)

Another features which might be on offer are ::

1. Compression of Database
2. UDF's
3. Replication and database synchronization

First five are must along with other would be the capabilities

Firebird embbeded. I am newbie, pardon.. :-D you'll find from firebird and it is UDF

Semoga membantu, wassalam.. (hopely help) :-D