The contractitems API returns a list of all items in a non-courier contract.
<eveapi version="2">
<currentTime>2011-10-28 11:08:58</currentTime>
<result>
<rowset name="itemList" key="recordID" columns="recordID,typeID,quantity,rawQuantity,singleton,included">
<row recordID="7118" typeID="16063" quantity="1" singleton="0" included="1"/>
</rowset>
</result>
<cachedUntil>2021-10-25 11:09:00</cachedUntil>
</eveapi>