Print edition: excerpting "fragments"
The first goal of a print edition is to collect information about fragmentary authors and their lost works. These pieces of information - called fragments - are excerpted from many different sources and duplicated in the new print edition.
The example in the screenshot shows a piece of information about Istros preserved by Athenaeus in the Deipnosophists (3.74e = 3.6). The passage of Athenaeus has been extracted and duplicated in the print edition as a fragment of a lost work of Istros (= F 12 Berti).
Generations of scholars have digged into preserved texts in order to find and collect scraps of information pertaining to authors who are lost. Such efforts have played a fundamental role in defining the notion of textual criticism and in preserving an invaluable cultural heritage. Moreover, they have produced sophisticated criteria for editing fragments and contributing, therefore, to the development of Classical philology.
The drawback of such a work is that excerpting fragments means decontextualizing quotations and allusions to lost works, producing an erroneous idea of information that can be understood only inside its context of transmission. The same term fragment is quite misleading, because in this case we don't have any original evidence and the supposed fragment is only the result of the work of the editor, who measures the degree of re-use of lost information and tries to calculate the percentage of original text preserved in it.
Another disadvantage is due to the fact that, especially in prose texts, is difficult to fix the beginning and the end of a quotation and therefore the extension of the fragment reproduced in the print edition. For different lengths of the same fragment in different editions, see the examples showed in the section about Plutarch.