IRIS databases are, in fact, ordinary Matlab struct objects (see the Matlab documentation for more on the struct class of objects). IRIS uses these struct objects as input and/or output databases in many functions (such as model/simulate). Moreover, there are a number of new functions extending the possibilities of the struct class, such as importing and exporting data from/into CSV files ( dbload and dbsave), processing batch jobs within databases (dbbatch), etc.
Check help data/contents for IRIS database functions.