One of the big problems that I have in writing reports is the often confused language that one sees within the laws and regulations. For example, any archaeological site, historic building, or place of strong community importance is a "cultural resource." Under California's environmental law, any cultural resource that is eligible for listing on the California Register of Historic Resources is a "Historical Resource" which includes prehistoric sites. However, archaeologists have long (as in well pre-dating the origin of these laws) made a distinction between historic and prehistoric sites (historic sites were occupied by people who came from a culture that produced written records, prehistoric sites were left by people who did not leave written records). But the term "prehistoric resource" doesn't mean anything in a regulatory sense, while "historical resource" means an important site/building/whatever that might be prehistoric, but might also be historic, and it sounds alot like "cultural resource" which is a generic term that says nothing about the status of the resource regarding the California Register.
Under federal law and regulation, the term "historical resource" means a cultural resource that dates to after European contact with the Americas. It doesn't mean anything regarding the eligibility for a cultural resource to the National Register of Historic Places (the federal equivalent of the California Register of Historic Resources). So, if you are writing a report for a federal agency, you can describe a site as a "historical resource" without worrying about triggering any alarms regarding register eligibility. If you are writing a report that will be reviewed by both a state and a federal agency (which is pretty common), then you simply have to avoid using the term altogether in order ot not be making claims about the eligibility of a resource for either register.
The problem is made more annoying when you consider that we often have to talk about historic-era resources, historic-era sites, cultural layers, and cultural deposits when we are discussing archaeological sites. So the terms "historic" and "cultural" are in very heavy use, and it takes frequent checking and care to ensure that we are not mis-stating things and using a regulatory term like "historical resource" (a site, whether prehistoric or historic, that IS eligible for the California Register) when discussing a "historic site" (which is a site with historic-era, but not prehistoric, materials that may or may not be eligible for the California Register). the presence of the words "cultural" and "historic/historical" become meaningless until you see what word immediately follows it, and there is a high likelihood that it will be a word that gives the sentence in which is appears a substantially different meaning, while looking very similar.
It gets rather confusing. Adding to the mess is that all of us have our own ways of keeping the different terms straight, but that each consultant and each regulator does so in subtly different ways, so the review process often contains far too much confusion regarding what, precisely, is meant by any given sentence, and a level of scrutiny is sometimes applied to each word choice that veers away from bordering on the silly and sails through loopy harbor out into the open waters of the sea of absurdity.
And yet you have to engage in this level of scrutiny in order to present accurate information that does not incorrectly make claims as to the legal status of a particular site.
The language seems to be a classic case of decision by committee, where the wording was eventually agreed upon in order to not piss anyone off, and everyone was at that point too tired to actually give much thought as to whether the regulatory language might not cause further confusion.