More detailed version of rules are here:
It means you may spawnkill in places,where you fighting for spawnpoint.
For example in Bremen map.The allies may kill with any kind of weapons including arty(exept mortar)axis first spawnpoint(the flag).Axis may kill with all weapons including artillery(exept mortar)and take the flag back as long the wall is blown up and flags gone.After that its fixed spawn for allies and any kind of Sk in there isnt allowed.
Next the Cp in there is capturable.both teams may kill there with all weapons(exept mortar) in any time as it will be capturable whole map.
After the allies has taken the flag/cp.Axis second spawn will be fixed the whole map and any kind of SK isnt allowed there.( read exeption in the rules! When you spawnpassing to fix the truck,you may shoot back only when you get shot first)
In some maps the mortar guy hides in spawn and shoots from there.That too goes under exeption and you may kill him as he technically shooted first.
Its spawnexit rule.You may use heavy weapons only on spawnexit,where has multible exits.(example Goldrush axis second spawn)
SK isnt allowed in multible exits.(unless its capturable)
Hope i understood what you asked and you got your answer.Feel free to ask for more