There are certain flags that affect the operation of MPI code that are usefull to know.
When an exit is set H, it will react to commands which has it as a prefix and not only if the command exactly matches the total exit name. As well, {&arg} will be set to the text after the exit name.
What does this mean? If you have an exit 'HELP', and the exit is not H, then only by typing 'HELP' can you trigger it. If you type 'HELP ME' or 'HELP MPI', nothing will happen.
If this same exit is set H, it will now react to 'HELP', 'HELP ME', 'HELP MPI', or else any other command that starts with 'HELP'. In addition, {&arg} will return '', 'ME', 'MPI', respectively. This allows you to have actions that have parameters that can be acted on by your MPI code. Note that the first space between the exit name and the arg is removed but others are left inside {&arg}. (Not fully verified).
Matching: When matching, the MUCK does a maximal match, such that if you have an exit 'HELP;HELP ME', 'HELP ME' uses the second one and gives an arg of ''. As well 'HELP ME NOW' gives an arg of 'NOW'.
This flag permits the {force:} command to control an object. (such as a puppet) Assuming as well as the flock set to allow that action or the player to to control it. (the object must be @flock'ed to the MPI action or to the MPI action owner)
While we're mentioning forcing and Zombies, this flag causes the object to echo everything to the owning player.