This method (on Microsoft Windows) writes a string with embedded environment variables (of the type REG_EXPAND_SZ) to the Microsoft Windows Registry. Embedded variables are in the form
%VARIABLE% and are expanded by Microsoft Windows to fill out the string when it is needed.
The Key entry must exist in the Registry. If the
Entry argument is not already in the Registry, a new entry is created and its value set. If the
Entry argument exists in the Registry for the
Key specified, the value of the entry is set to the new value.