smarts primitive "x" not supported

It seems the smarts primitive "x" (lower case) is not suppored by JChem 5.0.03. This is a relatively new feature of Daylight smarts, denoting ring connectivity, that is total ring bonds to the atom. Documented at http://www.daylight.com/dayhtml/doc/theory/theory.smarts.html, reportedly introduced by Daylight in v4.9, released in 2005. 'x" is also supported by OpenEye/OEChem.





Dear ChemAxon: please include support for "x".





Note that in OE smarts "x" is identical to "R". OE's "R" is different to Daylight's due to OE's aversion to SSSR.

Hi Jeremy,





Thank you for your note. We were planning to support x in SMARTS from JChem 5.2 (to be released at the end of this year), but we'll try to squeeze it into 5.1 (to be released this summer).





Until then, you may use the "rb" (ring bond) query property representable in MDL mol or Marvin(mrv) formats:


http://www.chemaxon.com/jchem/doc/user/Query.html#atprop





Best Regards,


Szabolcs