Having deleted some items from a scene, their textures are still listed in the material room. Does this mean the actual texture files remain in the scene file, or are these just links? How can I get rid of them? I looked through my collection of scripts, but I don't find one to delete surplus textures from a scene file.

They are just links, they will not be saved with the file. If the list gets too long simply save the scene, close Poser, reopen and reload the scene.

There is a "Remove detected nodes" option in the Material room but it only works for the current material.

Thank you Phil. For busy scenes, like outdoor ones with flowers, that list gets insanely long and difficult to manage.