Help me understand these memory statistics from Process Explorer

Question

I'm trying to do a very rough measurement of the amount of memory my large financial calculation requires in order to run. Its a very simple command line tool which prices up a large number of financial instruments and then prints out a result.

I decided to use Process Explorer to view the memory requirements of the program. Can somebody kindly explain the difference between the two fields labeled a and b in the screenshot:

I currently believe that:

The value labeled "a" (Peak Private Bytes) is the largest amount of memory (both actual physical memory and virtual memory on disk) which was allocated to the process at any instantaneous moment.

The value labeled "b" (Peal Working Set) is the largest amount of physical memory allocated at any instant during the life of the process.

Answer 1

From here:

The working set is the set of memory pages that were touched recently by the threads in the process. If free memory in the computer is above a threshold, pages are left in the working set of a process, even if they are not in use. When free memory falls below a threshold, pages are trimmed from working sets. If the pages are needed, they will be soft-faulted back into the working set before leaving main memory.

[Private bytes are] bytes, that this process has allocated that cannot be shared with other processes.

What "peak" means in that context should be obvious.