The Guidelines may be found here - on the newly revamped (and from this Blogger's perspective, newly inpenetrable) IPO website.
As the explanatory note published this week says:
Technological Protection Measures (TPMs) (also known as copy protection measures or DRM) are often used to protect copyright works, for example, through encryption on DVDs. TPMs can have a important role in enabling copyright owners (rightsholders) to offer content to consumers in different ways, as well as protecting against unlawful copying (piracy). EU and UK law protects the right of copyright owners to use TPMs to protect their works, and circumvention of such technology is illegal.
However, use of TPMs could potentially prevent activities that are permitted by copyright exceptions [surely they are always permitted, it is just that they can be lawfully undertaken without copyright holder approval]... The law therefore provides for a complaints process that aims to ensure that a TPM does not unreasonably prevent people from benefiting from an exception. The guidance on this page gives information on when and how someone may make a complaint, other steps that they should consider and some of the factors that may influence the outcome of a complaint.