In URBI, a variable can have a different meaning depending on whether you are reading or writting it: you can use the same variable to represent the target value of an effector and the current value measured by an associated sensor. This special mode is activated by the UObject defining the variable by calling UOwned after calling UBindVar. This call has the following effects
When URBI code or code in other modules read the variable, they read the current value. When URBI code or code in other modules write the variable, they set the target value.
When the module that called UOwned reads the variable, it reads the target value. When it writes the variable, it writes the current value.
If UOwned is not called, then the variable has only one associated value that is read or written by all modules and URBI code.