[Pharo-project] relation to squeak

Hello! One thing is not clear to me. How is Pharo related to standard Squeak? I know Pharo is a fork with its own mission, but is the development related? Do fixes in Pharo propagate upstream to Squeak? Is Squeak even considered "upstream"? Do fixes in Squeak propagate into Pharo? Automatically or manually? Or have they started being developed completely independently from some point in time? -- Milan Mimica http://sparklet.sf.net