I found the following concepts. Or "rules" if you like.
- In the opening speedy development is paramount
- A pawn move is not a development move
- Only pawn moves that occupy or support the center are allowed in the opening
- Don't move the flank pawns in the opening, unless it is a closed position where development is slower
- Maximum two pawn moves in the opening
- Win tempo's by threatening enemy pieces
- Develop with one move per piece
- When your opponent does a non development move, you can do likewise without getting behind in development
- Don't trade pieces in which you have invested much tempo's
- Liquidate the center when your development is impeded
- Method 1: exchange with gain of tempo
- Method 2: liquidate the center followed by a development move or a freeing move
- Mobile center pawns are criminals that should be eliminated or put under severe restraint. Prison or death. Or both.
- If you chase a piece away, beware that it has no better place to go where it can maintain itself
- Keep your center intact whenever possible
- Make your own center pawns mobile by undermining the restraint
- Don't grab pawns in the opening, there is no time for that
- Unless it is a center pawn. But that is motivated by the center, not by the wood.
18 concepts. Not bad. Needless to say that you can break the rules when there is a good reason for it. Just be aware that you are breaking the rules and be sure that your reason is valid.
Most concepts are familiar. Yet I'm not aware of it during the opening phase. That must change.
The concept of when to liquidate the center is new to me.