What i know is that the first time if any dataset(member) is created and data is kept that is called baseline and if suppose next time the same data has been modified then this change will be saved in version 1 of that baseline. so that one can distinguish between the original data and the modified data.Hence endevor is used for configuration management.
I know only this much of knowledge.
What Aiswhary wrote is correct. Just wanted some more elaboration.
Endevor maintains two libraries or you can say as MCF(master Control Files) files. One is Base lib and other is Delta Lib. Both are VSAM files.
Each Stage in Endevor contains two VSAM files to represent these above two libraries. When an element is first time added into Endevor, the base lib contains the element and the subsequent changes are stored in delta lib as a version number. If you browse these above VSAM files, then you can see some codes which are not understandable. Usually, the Last qualifer for these Libs are .MCF.