Icon Names: Lenght Limit?

During the migration from OH1 to OH2, I copied my icons from webapps/images to <openHAB 2 conf>/icons/classic. But they did not appear on the webpage.

The icon name I use in OH1 is e.g. KNXUF_scene_living. After changing the name to a_b_c, or to scene_living the icon appears correctly in OH2. But K_scene_living does not work, either.

Is there a length limit for icon names?

Update: knxuf_scene_living works, so: Are we not allowed to use capital letters in icon names?

Thx G.

That might be host system dependent i.e. Windows, Unix, …