Definition of Interface Agreement
An interface agreement is a document that defines an interface between two teams / locations / functional responsibilities.
It may typically include (or refer to) battery limit drawings, interface matrix, or interface register, for example.
It may be signed by both parties when agreement is reached, but not always.
Used more by stakeholders that “own” part of a project, rather than between contractors (who refer to their contract) - but see the green note below.
An Interface Plan is an agreement between interfacing parties regarding scheduled access to 'contract objects' prior to load out and delivery - for example, for testing of subsea control units, umbilical, etc.
Note that the Project Interface Management Plan is a core project document that defines how interfaces will be managed, and is described further here.
Interface Agreement is similar to Interface Document.
Some contractors may refer to an Interface Issue that has been agreed (and possibly signed) as an interface agreement.