-46 recurrent practices as well as unwritten rules in all relationships (prisoners-staff, among staff, among prisoners). Further there are mental models (cultural violence), such as the beliefs, attitudes and values of everybody working and living in prison. These factors provide information on how prisons are organised and why things are happening in a certain way, which is essential for an in depth understanding of the problem of prison violence and its root causes and for putting forward recommendations for change. A thorough understanding of patterns, underlying structures and mental models can furthermore help monitors look beyond statics and recognise the hidden dimensions of violence, such as fear of reprisals, retaliation, shame, hesitation to disclose vulnerabilities and weaknesses or, more generally, a lack of trust in prison authorities and the judicial system. NPMs should further complement their understanding of prison violence by integrating multiple perspectives and gathering data and information about prison violence from other stakeholders involved, such as an Ombudsperson’s office (if established), NGOs and volunteers, the probation services, lawyers, journalists and media, families of detainees, prison chaplains, former detainees and prison researchers. Cooperating with several stakeholders can be key to fully grasping the problem of violence in a country’s prisons, understanding what works best to prevent prison violence and, ultimately, developing a monitoring strategy as well as establishing adequate processes and procedures for encouraging change (see also below, § 4.2). 4.1.2. Gaining a good knowledge of standards and clarifying them when they are too vague NPMs should have a good knowledge of all standards relevant to preventing violence in prisons to assess whether the legal and policy framework for violence prevention of a particular MS is in line with international standards and, if necessary, put forward recommendations for change to the authorities. Moreover, if international standards are too general and not clear enough, NPMs can also suggest own, more precise criteria to