Main Lotus Notes workstation dlls and their meanings

If you list the .dll files that are installed in the Lotus Notes workstation, you will see that for example in R8.5 there are more than 300 dlls.

However the main (or most known) dlls are three:
nnotes.dll
nnotesws.dll
nlsxbe.dll

The more important is nnotes.dll that is the Lotus Notes engine. This dll is also present in the Lotus Domino server installation. This dll contains all backend functions that are used by Lotus Notes. This dll exports all NSF and other backend functions.
In fact the Notes C API is in fact a documentation of some functions exported from this dll. This dll exports nearly 13.300 functions from all these functions only 1100 are documented in the Notes C API reference.
The Lotus Notes workstation in fact is just a program that uses this dlls and provides services in a graphical way.
The server tasks (update, amgr, ...) are just programs that uses functions from these dlls.

Now the nnotesws.dll implements all visual aspects belonging to the Lotus Notes workstation. It renders the view, the forms, the workspace and so on... it is like the shell32.dll file in Windows. The nlnotes.exe program delegates most of the visual aspects to this dll. When you select files from a view and you drag them into another place all is managed by this nnotesws.dll. When you open an attachment, it is managed by this dll.
To put a single example. Suppose that you copy part of the email you are viewing. In this case nnotesws.dll calls the OleSetclipboard API filling the information.

nlsxbe.dll is all about programming in Lotus Script and formula.
It is like a kind of wrapper that translates the Lotus script code (or formula code) into Notes C API calls.

There are many other dlls, all of them are important... but these 3 dlls are known by many people but not all them know what they are related to.