1aa. With cannon in location A1, and pao buttress in A2, how to cannon the target at location A4? how to target A6? I know that A1----A2 (buttress) --->A3 (target) is: paW. But how to write A1----A2 (buttress) --->A4 (target)?
Note that the a1-a2-a3 hopper would be pafW. If you do not restrict the direction of the second leg, like in paW, it would also allow a1-a2-b2.
For a1-a2-a4 it depends on whether you want to put any conditions on a3. If that must be empty for the move to be allowed, you would write pafafW. So you would start with a 'hop on' leg (p) far reaching the 'mount', and then continue with two more steps in the same direction (f) instead of just a single step. By default the target square of a non-final leg must be empty, so anything on a3 would block the move. If you don't want that, you have to overrule the default by explicitly writing what the target square can contain: empty (m) or any piece (p). So you get pafmpafW when you want to allow the move in all cases (and thus effectively ignore a3).
1ac. On diagonal Pao. With cannon in A1, and buttress in D4, how to cannon target E5? How to target F6? How to target G7? How to target H8? How to target I9? How to target J10 ?
The diagonal hopper that must land directly behind the mount, but can have this mount at any distance (sliding towards it) would be written as the corrsponding slider (so B for diagonal), but to indicate that it no longer slides beyond the mount you would write an extra y before the a: pyafB. If you would want it to land two squares behind the mount, this would become pyafmpafB. The mp would indicate that the square between the mound and where the piece lands can be either empty of contain a piece. If you want to require it is empty you should have written pyafafB, which by default is the same as pyafmafmcB.
Note that the a1-a2-a3 hopper would be pafW. If you do not restrict the direction of the second leg, like in paW, it would also allow a1-a2-b2.
For a1-a2-a4 it depends on whether you want to put any conditions on a3. If that must be empty for the move to be allowed, you would write pafafW. So you would start with a 'hop on' leg (p) far reaching the 'mount', and then continue with two more steps in the same direction (f) instead of just a single step. By default the target square of a non-final leg must be empty, so anything on a3 would block the move. If you don't want that, you have to overrule the default by explicitly writing what the target square can contain: empty (m) or any piece (p). So you get pafmpafW when you want to allow the move in all cases (and thus effectively ignore a3).
The diagonal hopper that must land directly behind the mount, but can have this mount at any distance (sliding towards it) would be written as the corrsponding slider (so B for diagonal), but to indicate that it no longer slides beyond the mount you would write an extra y before the a: pyafB. If you would want it to land two squares behind the mount, this would become pyafmpafB. The mp would indicate that the square between the mound and where the piece lands can be either empty of contain a piece. If you want to require it is empty you should have written pyafafB, which by default is the same as pyafmafmcB.