The present paper deals with the problem of: How to understand and apply the term Formation. It points out the necessity of a prompt revision of the Stratigraphic Code and its Explanation which fall behind the rapid progress of the last fifteen years. The prineiple of priority in the selection of existing stratigraphic units is here questioned. Some confusions in the concept of Formation should hereafter be avoided. Finally a brief account on the time-transgressive nature of the Devonian Lianhuashan Formation is added.