docs: function (cb) {
  
                  const filters = req.linz.model.list.filters;
                  const formData = session.list.formData;
  
                  // Make sure we have some filters.
                  if (!filters) {
                      return cb(null);
                  }
  
                  // Find the alwaysOn filters, that have a default.
                  const alwaysOnWithDefault = Object.keys(filters).filter((key) => filters[key].alwaysOn === true && Object.keys(filters[key]).includes('default'));
  
                  if (!alwaysOnWithDefault) {
                      return cb(null);
                  }
  
                  // If it already exists, turn it into an array for easy manipulation.
                  if (formData.selectedFilters && formData.selectedFilters.length) {
                      formData.selectedFilters = formData.selectedFilters.split(',');
                  }
  
                  // If it doesn't exist create a default array.
                  if (!formData.selectedFilters || !formData.selectedFilters.length) {
                      formData.selectedFilters = [];
                  }
  
                  // Make sure the alwaysOnWithDefault filters have entries in session.list.formData.selectedFilters.
  
                  alwaysOnWithDefault.forEach((key) => {
  
                      const filter = filters[key];
  
                      if (!formData.selectedFilters.includes(key)) {
  
                          // Add to the selected filters list.
                          formData.selectedFilters.push(key);
  
                          formData[key] = filter.default;
  
                      }
  
                  });
  
                  formData.selectedFilters = formData.selectedFilters.join(',');
  
                  return cb(null);
  
              }