help---what means 'package' in monkey -p package

[lqxkj520@gmail.com]

i am a fresh android developer from China, when i turned into a emulator shell to do some stress test , but i don't know about the ALLOWED_PACKAGE and MAIN_CATEGOR represent for, where can i get the detail usage about monkey but not just show belows,

$ adb -e shell
# monkey
usage: monkey [-p ALLOWED_PACKAGE [-p ALLOWED_PACKAGE] ...]
[-c MAIN_CATEGORY [-c MAIN_CATEGORY] ...]
[--ignore-crashes] [--ignore-timeouts]
[--ignore-security-exceptions]
[--monitor-native-crashes] [--ignore-native-crashes]
[--kill-process-after-error] [--hprof]
[--pct-touch PERCENT] [--pct-motion PERCENT]
[--pct-trackball PERCENT] [--pct-syskeys PERCENT]
[--pct-nav PERCENT] [--pct-majornav PERCENT]
[--pct-appswitch PERCENT] [--pct-flip PERCENT]
[--pct-anyevent PERCENT]
[--pkg-blacklist-file PACKAGE_BLACKLIST_FILE]
[--pkg-whitelist-file PACKAGE_WHITELIST_FILE]
[--wait-dbg] [--dbg-no-events]
[--setup scriptfile] [-f scriptfile [-f scriptfile] ...]
[--port port]
[-s SEED] [-v [-v] ...]
[--throttle MILLISEC] [--randomize-throttle]
COUNT