I've recently been to Tyrol and saw
potential tier 5 routes signed. I made some research (see
SSC or
autobahn-online) and it seems that two states sign their secondary state routes. The status is as follows:
autl1 - Burgenland Landesstraßen 1. Ordnung (not signed)
autl2 - Carinthia Landesstraßen L (not signed)
autl3 - Lower Austria Landesstraßen L (not signed)
autl4 - Upper Austria Landesstraßen 1. Ordnung (signed on km posts)
autl5 - Salzburg Landesstraßen 1. Ordnung (usually not signed)
autl6 - Styria Landesstraßen L (not signed)
autl7 - Tyrol Landesstraßen L (signed on direction signs and km posts)
autl8 - Vorarlberg Landesstraßen L (not signed)
autl9 - Vienna Hauptstraßen A (system is not numbered but just indicated with street names)
autl7 is in preview since yesterday, autl4 will follow shortly.
btw: The odd system suffix number is the official
ISO 3166-2:AT code (alphabetical order of German state names).