Force types are a fast way to send long messages. Message types in the range from 1073741824 to 1999999999 are special force types that bypass the normal flow control mechanisms and do not match the -1 wildcard.
Messages of force types are discarded if no receive is posted at the time of their arrival at the destination. Therefore, a force type message should be sent only if it is certain that a receive has been issued for it. Force type messages are sent faster because the message avoids the system buffer and goes directly to the buffer of the receiving node.