Layer Management > Use (Manage Menu)

This command can be used to use layers by identifying objects that are assigned to the desired layers. To use a layer means to clear the attribute "Ignore", i.e. objects assigned to it will be considered during snap point detection.

Choose the objects whose assigned layers are to be altered. Click on objects to choose them, including objects in locked layers.

After identifying the objects, their layer assignment is determined and all affected layers are used.