Belgian rail lines have official numbers, and on many lines these numbers are placed on trackside poles, primarily close to points where lines diverge. Some lines have known different numbers in their history, for instance as a result of closure of line sections or a change in the pattern of direct rail connections for passengers or goods.

                     

The lower numbers are to be found on the older and more important parts of the rail network. Apart from that, the numbering is based on geographical location to some extent.

                   

 In the 1960s, industrial spurs and freight only rail sections have been given numbers above 200. N.B.:. 

 

This network numbering system is generally different from the numbering of passenger services in the timetable.