DP/Flex/DFO/DH

Question
Could you please explain the difference in these players?  I am very confused on when to use, how to use, and when and how a player is "tied" to another player.

Thanks'
JB

Answer
Jason,

I will explain the DP/Flex rule.  This is what ASA and High School use.  The DFO/DH are used by other associations and could be similar, but I am not familiar with the details

When using the DP/Flex rule a team has 10 players in the line up.  Your first 9 players are your offense.  One of the the first nine is your DP and doesn't play defense.  The 10th player in the line up is the Flex player.  The Flex player plays defense only.  

Here is where it gets a bit interesting.  Any nine of the ten can play defense.  The only issue you can have here is if the DP plays defense while the Flex player doesn't.  This is considered a substitution and the Flex player has left the game.  The Flex player can re-enter.  The substitution rules get a bit more complicated but this is the general idea.

Tom