Explanatory notes form a document containing the information that cannot be included in the main body of the sheet and border for obvious reasons of space. The explanatory notes are to be considered an integral part of the sheet which may be completed by diagrams, sections, tables, photographs and any information deemed useful. They may also include sheet excerpts on a scale over 1: 50,000 in order to represent complex tectonic and/or stratigraphic areas in greater detail.

As well as supplementing the sheet, the explanatory notes can also help to draw attention to unsolved problems and questions requiring further study, as well as helping to compare different interpretations.

It should be stressed that as the explanatory notes represent a technical-scientific instrument used by the entire community of geologists – and not only – it is important to begin by setting out the basic data as clearly and simply as possible, then proceed in greater analytical detail before reaching the concise information and interpretations of use to "experts" and specialists.

The minimum content of the explanatory notes are as follows:

The scope of the various themes will obviously depend on the type of area concerned and, therefore, the type of geological problems involved. Chapters, paragraphs and sub-paragraphs may be added for the purpose of examining given themes in greater depth (for example, petrography, sedimentology, marine geology). For the purposes of uniformity, all explanatory notes must comply with the guidelines in the Quaderni, series III, nos.1 and 2 with regard to general guidelines.

The titles of the various arguments may contain the name of the Author or Authors in brackets.