Answered By: Leon Research & Writing Studio Last Updated: Jan 09, 2018 Views: 586
The Chicago Manual of Style calls this kind of footnote "Substantive notes."
From the Chicago Manual of Style, section 14.39:
Substantive, or discursive, notes may merely amplify the text and include no sources. When a source is needed, it is treated as in the example in section 14.38 or, if brief and already cited in full, may appear parenthetically, as in the following example:
1. Ernst Cassirer takes important notice of this in Language and Myth (59–62) and offers a searching analysis of man’s regard for things on which his power of inspirited action may crucially depend.