What are forensic 'class characteristics' of evidence?

What are forensic 'class characteristics' of evidence?

When we are dealing with class items of evidence, that is, items where we have made a comparison but we can only limit the comparison to a small number of individuals or a small group and not to one single person, and that may be very frustrating to a prosecutor or to a jury to hear. But, the point of fact is that often physical evidence cannot be linked to only one person. It is important to understand that kind of evidence, and that kind of class of evidence is very important in building a case. It will collaborate other types of police investigative evidence that may be created during the investigation; confessions, eyewitness testimony and the like.