The WBS can be either expressed using a list with indention or using a hierarchical tree.
Delph Printers Project 1.0
Project Management 1.1
Administration 1.1.1
Assembling 1.3
System Engineering 1.2
Multilayer PCB 1.3.1
Design Work 1.2.1
Reporting 1.1.2
Frame assembling 1.3.2
Design Approval 1.2.1
Paper Transport Ass 1.3.3
Transfer corona Assembly 1.3.4
Purchase of Materials 1.2.3
Scanning Assembly 1.3.5
Toner Cartridge 1.3.9
DC Power Supply 1.3.8
High Voltage Power supply 1.3.7
Fuser Assembly 1.3.6