working folder in which build is started
build number assigned by TeamCity
VCS changelist number, where XX is the number of VCS root (1, 2, etc.)
Please refer to Agent Details|System properties page of the TeamCity web UI to see properties defined on particular agent.
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On build configuration administration screens the properties can be referenced by %system.<property name>% and %env.<property name>%. build.working.dir is a special case and it is referenced as is, without prefixes.