# Oracle Integration Specifications (OIS)
ois JSON object, in the
config.json file that defines an Airnode, is an
integral part of an Airnode's understanding of an API's specification and its
endpoints. OIS provide a description of API endpoints and maps Airnode endpoints
to them. There can be more than one OIS object in the
config.json file as
Airnode can serve endpoints from more than one API.
Learn more about Oracle Integration Specifications (OIS) in its versioned document set.