Updating from Praxiteles' post for clarity and corrections.
Decay Counters, Left to Right, Top to Bottom:
Small Taskforce Tactics?, Infantry Practical, Infantry Theoretical, Militia Practical, Militia Theoretical, Equipment Practical, Equipment Theoretical, Artillery Practical, Artillery Theoretical, Rocket Practical, Rocket Theoretical, Naval Engineering
Tactical Bomber Tactics, Small Ship Theoretical, Big Ship Theoretical, Carrier Theoretical, Submarine Practical, Submarine Theoretical, Electronics Practical, Electronics Theoretical, Armor Practical, Armor Theoretical, Aeronautics, Fighter Tactics
Fighter Theoretical, Strategic Bomber Tactics, Armor Focus/Blitzkrieg Tactics??, Combined Arms Tactics, Centralized Execution, Large Unit Tactics, Individual Courage, Naval Training, Carrier Practical, Large Ship Practical, Submarine Missiles Practical?? , Piloting
Empty, CAS Practical, TAC Practical, NAV Practical, STR Practical, Mechanics, Chemistry, Bombing Practical??, Bombing Theoretical??, Nuclear Engineering, Nuclear Physics, Large Taskforce Tactics?
Missing from HoI 2 and corresponding replacements if any:
Industrial Engineering [Factory symbol], Technical Efficiency [Gear symbol], Management (subsumed to Leadership?) [Star symbol], Mathematics [Square Root of X Squared symbol], Training (subsumed to Land Formation Practical) [Book symbol], Naval Artillery (subsumed to Artillery) Decentralized Execution, Aircraft Testing (subsumed to Aircraft Type Practical), Infantry Focus, Seamanship (subsumed to Ship Type Practical)