Hi guys. As you may notice, I always try to push in the direction of a VM where we can have both things: a) a really cooler super fast VM for production super critical applications and b) the most-flexible-possible VM for doing reasearh and experiment. Now I was thinking the following: we have one free bit in the ObjectHeader. Let's say you are experimenting with something and you would like to tag objects, such as, "traversed", "processes", "isProxy", etc. To do that small experiment you need to modify the VM, adapt the bit, code the primitives, build the VM, put the smalltalk side part etc etc. So I was thinking why not providing such small functionality out of the box? the idea would be not to give semantics to the bit since each user will do that. So we just provide the VM with 2 primtives, one to get the value (#getBitValue) and one to set it (#setBitTo:). Choose the names you want. Then we do not integrate nothing in our images that use such bit, there won't be colisions. Then each guy who wants to experiments with that, can use the primitives and do what he wants. Some people is doing something with its bit: Jean Batiptse is doing XXX, I am doing YYY, etc. Either in his work or mine, there are much more changes that just that bit, so in anyway, I will end up needing my own VM. Finally, I could help in providing the code if it is needed. So, what do you think? -- Mariano http://marianopeck.wordpress.com