Sublime text key-bindings怎么写？

[
{ "keys": ["f12"], "command": "reindent"},
{ "keys": ["ctrl+alt+n"], "command": "new_snippet"},
{ "keys" : ["n","n"], "command": "advanced_new_file",
"context":[{"key": "setting.command_mode","operand": true}]},

{ "keys":["j","j"], "command": "exit_insert_mode",
"context":[
{ "key": "setting.command_mode", "operand": false},
{ "key": "setting.is_widget", "operand": false}
]
}
]

这些command是自己命名的吗？http://www.sublimetext.com/docs/commands这里没有上面的命令。