Question about plea deals

Lawyers tell me that most/all plea deals have a boilerplate paragraph stating that what isn't written in the plea deal doesn't count. For example in alleged WikiLeaks courier Matt DeHart's plea deal -- http://douglaslucas.com/files/DeHart_PleaAgreement.pdf -- on PDF page 13 there's this text: "29. No promises, agreements, or conditions have been entered into other than those set forth in this Plea Agreement, and none will be entered into unless memorialized in writing and signed by all of the parties listed below." Does anyone know what the generic term/name is for that kind of paragraph in a contract (preferably, in a plea deal specifically)? I ask the lawyers and they say there is such a generic term and they just can't remember.