> For the complete documentation index, see [llms.txt](https://docs.verifone.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.verifone.com/functional-specification/select_app.md). # select\_app {% columns %} {% column width="33%" %} ![](/files/4THNrI27YZMCJk0CVda5) {% endcolumn %} {% column %} **Description** If there are multiple Application Identifiers (AIDs) to choose from, the customer will be asked to chose between the AIDs. If there is only one AID or if the terminal can choose the AID based on the priority list, then this will be skipped and AID will be selected automatically. This will only be shown for chip cards. Contactless transactions will select the application with the highest priority. \ **Error Scenarios** If the customer removes the chip card, the transaction will be cancelled and no reversal will be generated If the Application Identifier (AID) that the customer selected fails, the customer will be asked to chose from remaining AIDs. If no other valid AIDs are available, the customer will be asked to fallback to swipe the card If the customer cancels the transaction, Transaction Cancelled, user aborted message will be shown If the screen times out, Transaction Aborted, user timeout message will be shown If the device crashes or device reboots while on this screen, when the payment application restarts or device boots up, no power failure recovery will happen {% endcolumn %} {% endcolumns %} \--- --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.verifone.com/functional-specification/select_app.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.