Mainboard
Appearance

The Mainboard acts as a container for 1 to 3 virtual components. By default all mainboards contain the UEFI component. The second tier also comes with an NVRAM (Non-volatile RAM) equipped, and the final tier also includes a TPM (Trusted Platform Module), but this final component is not implemented yet. Therefore the tier 3 mainboard acts like a tier 2. There is and will not be any difference in terms of UEFI or NVRAM size as to offer maximum compatibility of programs / OSes.
Provided component
This item provides no components via the Component Registry, but instead they are offered as part of the Computer component. See the three properties uefi, nvram and tpm in Computer#Provided component.