Abstract: Task extensions for a proof-of-service (POS) system allow easy customization without requiring modification to the POS application itself. Current preferences capability is used to specify new tasks, which are downloaded to the device during an administrative sync process. The new workflows are detected at runtime. This provides a way to collect additional customer-defined data associated with a given task. Ideally, task extensions could be used with both the existing tasks (delivery and pickup) and with new tasks that would be defined by a customer. Data collected by the workflow extension is returned as an XML-tagged string of data elements to the legacy system, which would be responsible for parsing the data. Some rudimentary data validation on the client may be included by adding attributes to the XML-tags that define the UI's data collection elements.