Group selected animation keys in an F-Curve the «Graph Editor»

There is a similar method in Edit Mode: Vertex Group. I need something similar but with animation keys in the Graph Editor.

Description of video: A demonstration of selecting vertices in a mesh and then adding them to a vertex group. This is followed by selecting keyframes in an F-Curve and a question mark — meant to indicate the desire for the equivalent functionality, a sort of "vertex group" for keyframes.

Advantage / application animation key grouping:

Analog - NLA but in one action. Replacement / alternative to NLA. Place the grouped cycles of different gaits in one action further along the timing, in order to substitute one or another grouped part of the desired cycle in the right place of timing in the process.

blender.stackexchange.com/questions/249598/how-to-group-selected-animation-keyframes-in-the-graph-editor