The current Austrian locomotive numbering system has been in place since 1985. In brief the numbering for each locomotive can be determined by reviewing 3 charts for each digit followed in some cases by a computer check digit.
1st Digit – Traction Code: 0-steam locos, 1-electric locos, 2- diesel locos, 3- steam railcars, 4- electric multiple unit, 5- diesel multiple unit, 6- driving trailers, 7- intermediate trailers, 8- (NA), 9- tenders
2nd Digit – Origin Code: 0-5- Austrian and German standard, 6-8- pre-DRB, 9- foreign types. For electrics: 0-7- AC, 8- AC/DC, 9- DC. Note: 1 is added to the second digit to represent developments of a type thus a Class 1116 is a further development of Class 1016.
3rd and 4th Digit – Utilization Code: Steam Locomotives – 01-39- passenger tender, 40-59- freight tender, 60-79- passenger tank, 80-96- freight tank, 97- rack fitted, and 98-99- narrow gauge. Diesel Locomotives – 01-19- express over 2000hp, 20-39- heavy freight over 2000hp, 40-59- mixed traffic 1000-2000hp, 60-64- “B” wheel arrangement under 1000hp, 65-69- “C” wheel arrangement under 1000hp, “D” wheel arrangement under 1000hp, 80-89- self propelled snowplough, 90-99- narrow gauge. Electric Locomotives – 01-19- express, 20-39- heavy freight, 40-59- mixed freight, 60-69- shunting loco, 70-89- older types, 90-99- narrow gauge. Railcars – 01-19 express, 20-59- local, 60-79- baggage, 80-89- light railbus, 90-99- narrow gauge.
A Computer Check Digit is used to double check that all digits are correct, this final digit in the locomotive number is not always displayed on the loco. To verify the class and running number digits are multiplied alternately by 2 and 1. The resulting digits are added together and deducted from the next whole 10 number thus revealing the correct “check digit”.
Example: for the OBB electric shunting loco #1063 028 the check number is thus calculated: 1×2, 0x1, 6×2, 3×1, 0x2, 2×1, 8×2= 2+0+1+2+3+0+2+1+6=17. 20-17=3 thus the full number for this OBB loco is 1063 028-3.
My guide to understanding European train classifications is the excellent series under the title European Handbooks. This highly recommended series of books on various European railways is indispensable.
Reference material: Austrian Railways, published by Platform 5, written by Roland Beier and Brian Garvin.