| A common tool in these maps is an isogloss, a line separating areas where different variants of a particular feature predominate. |
| All words belonging to the same isogloss must have sound correspondences and clear similarities in form and meaning. |
| At the same time, there are no strong isogloss bundles between areas VI and VII, or between III and IV, which explains the absence of transitional areas between them. |
| Here again, the participating Taimyrian languages Forest Enets, Tundra Enets, Nganasan, Dolgan and Evenki behave similarly, but this isogloss stretches further south and east. |
| However, the High Franconian dialects spoken up to the Speyer line isogloss in the north, are also considered part of the larger Upper German dialect group. |
