The years in the timeline are mainly based on the labels. The base marks are then arranged in chronological order based on the labels they comes with. 

Time periods for labels and marks are presented as: 1955-1960. This mean that the label or mark was used from 1950 until and including 1960.
 

In this guide I use the terms embossed, debossed and incised base marks. Embossed and debossed marks are both moulded marks. The embossed mark is raised and the debossed mark is depressed in the surface. The incised mark is impressed in the clay when it was still wet. The incised mark can be made by handwriting or by a stamp. Sometimes it is very difficult to determine if it is a debossed, moulded mark or an incised mark made by a stamp.