Outputs
Here you will find the respective arrays with the names of the properties stored at the geometry. You will get an array even if the corresponding property on the geometry was not saved at all. If a property is basically available at the geometry, such as UV coordinates at a cube, but no UV coordinates were saved under its own name, the array output for UV will have a length of 1, but will not contain a string.
The situation is different for properties that are not present by default, such as Normals, colors, or weightings on a cube geometry. There, the output array then has a length of 0. Such properties must first be defined with a Set Geometry Properties Node. This then also offers the possibility of assigning a name for these properties. Selections can still be easily saved with a save Selection Node.