gives the different representations of env mapping in .w and .prm files
a common access.
Enumeration values:
- On
- For .w: Set enable-env bit.
- For .prm: don't set disable-env bit
- Off
- For .w: Don't set enable-env bit.
- For .prm: don't set disable-env bit
- Disabled
- For .w: Don't set enable-env bit.
- For .prm: Set disable-env bit