The series would be numbered 1001-1010 and had 6 axles in a 2-2+2+2+2-2 or (1A)Bo(A1) configuration. The arrangement was similar to the widely used 1′Do1′ arrangement of this period, but with the outer driven axles articulated as a bogie with the unpowered carrying axles, rather than the carrying axles being articulated as single axle pony or Bissel trucks. This configuration was already used successfully on the electrified railway network on Java, then a Dutch colony, but in the Netherlands it was a failure due to its complicated technology and high maintenance.