These are older records, with the majority having publication dates of 1985 or earlier. You can see which organization was responsible for providing a record from the Document Number, the series of alpha characters at the beginning identifies it. Author s designates an abstract taken from the original document verbatim, except for very minor changes such as converting Greek symbols to words.
Author s modified designates an author s abstract with modified or supplemental information.
These designators are found at the end of the abstract enclosed in parentheses. But, of course, there are exceptions. This indicates that the text is taken verbatim from the original document. It is not an original abstract. You will also notice that many IND abstracts are indicative, rather than information, abstracts and give a general overview of the cited document.