* Homology variation (e.g. alkyl, aryl)
* Conditions for generic features: occurrence lists, dependency, etc
=Demonstration of a markush Markush structure= The specific structures are * Undec-1-ene-5-one* Dec-1-ene-6-one* Undec-1-ene-7-one These specific structures are represented by using one markush structure. And it is [[Image:Alkenone.jpg|750px|thumb|center|Alkenone]]