#org : Starts writing data to this offset. Only the last 6 hex digits of the offset are used, as GBA can't handle more than this. If you don't define it in hex, then it is converted to hex first (internally).
#define : Not used in decompiled scripts. Applies an alias to a value. (eg. #define dead-food 0xDEADF00D , or #define newspace FREESPACE100). If you define something as free space, use the format "#define NAME freespaceAMOUNT", where name is what you want to call the free space and amount is how much space you need, in bytes in hex.
#raw : Writes 1 byte to ROM. In other words, if you are trying to write something bigger than 255 (0xFF) then you need more #raw blocks, or a "." command.
. : Not used in decompiled scripts. Writes a hex string to a ROM. (eg. ". Deface dead f00d" would write the hex string "DE FA CE DE AD F0 0D" to ROM)
jump : Continues script execution at a different position.
call : Same as jump, but a "return" will cause it to return to the position this command is at.
message X/showmsg/waitbutton/closemsg : Shows the message at offset X.
msgbox X/callstd MSG_NORMAL : Same as above, but not as flexible.
loadpointer 0 X/callstd MSG_NORMAL : Not used in decompiled scripts. Now you're just being silly.