Hi, Methods, AST Nodes and all Ring Definitions can store properties. Now in Pharo4 update 307, Yuriy Tymchuk extended this idea to Behaviors. They are not stored when saving code (filing out or MC), as this would be on top (as are the Pragmas on Methods build on top of properties). TODO -> unify API across RB/CompiledMethod/Ring -> add properties to the Variable meta-objects (there is already a proof-of-concept in class LinkWrapper for one special kind of property) -> For sure there are bugs (while writing this I had one idea of one already⦠need to check) This will not be used by the system itself for now, therefore we opted to store them not in an ivar but a classVar dictionary, so they do not take any space when not used (like CompiledMethod properties where realised in the beginning, too). Marcus