Several notes on the experience.
1. Math. methods and algorithms: optimization (genetic algorithm, linear programming), graph theory applications, image processing, Fourier transforms, data filters.
2. Software: general-purpose libraries (containers, Excel automation, object DB, hardware drivers), measurement systems (physics), accounting systems (wholesale trade).
3. Design/development: full cycle (requirements, architecture, design, coding, testing, documenting, support). Using C++ (9 yrs.), VB (6 yrs.), SQL, UML, XML; now learning C# and Java.