Limitations of the Open Babel SMARTS Implementation
The Open Babel implementation of SMARTS is not bug-free, nor does it support everything in the Daylight Toolkit. In particular, it does not currently support:
- Component-level grouping (i.e., "(C).(C)")
- Use of non-tetrahedral chirality
This list may not be complete. Please e-mail the  mailing list if you have questions about the SMARTS support in Open Babel.