Under the section "Software authenticity" does it mention that the secure boot requirement appears to come from article 3, §3 (i).
Quoting article 3, §3 (i):
> radio equipment supports certain features in order to ensure that software can only be loaded into the radio equipment where the compliance of the combination of the radio equipment and software has been demonstrated.
The opening of §3 is:
> Radio equipment within certain categories or classes shall be so constructed that it complies with the following essential requirements: