To set NLS_LANG environment variables:
Define values for these variables in the same way you define other environment variables on your base operating system, keeping in mind platform-specific rules such as path length, etc.
For example, to set NLS_LANG for Microsoft Windows:
Note The Windows registry is highly sensitive to changes. Only change environment variables if absolutely necessary. If you make a mistake, click Cancel and restart.
Note: If you want to use any NLS feature, you must at least set NLS_LANG so that the product can locate the NLS components.