{\"targeting\": {\"sport\":[\"rugby\",\"cricket\"]}}**\n - The response body must be JSON, but the actual structure of that data need not match the structure here. Refer to Fast Fetch Network specific documentation for the required spec. (for example, if using DoubleClick, refer to DoubleClick docs).\n\n### RTC Error Pingback\n\nRTC supports sending a 1% per-page sampling of RTC errors to specified errorReportingUrl's. (I.e. 1% of pages will send RTC error pingbacks for all RTC errors that occur on that page). For any given RTC callout URL, a corresponding errorReportingUrl may be specified, which will receive pings for, and only for, errors that resulted from the associated RTC callout. For example, you can not specify one errorReportingUrl that receives batched pings for all RTC callouts from a page. The errorReportingUrl must be a secure URL that uses HTTPS.\n\nVendors may specify an errorReportingUrl within their config in callout-vendors.js, e.g.:\n\n```text\n/** amp-a4a/0.1/callout-vendors.js */\nvendors: {\n \"vendor1\": {\n \"url\": \"https://vendor1.com/slot_id=SLOT_ID\",\n \"macros\": ['SLOT_ID'],\n \"errorReportingUrl\": \"https://vendor1.com/e=ERROR_TYPE&h=HREF\",\n }\n};\n```\n\nFor custom URLs specified by a publisher directly on the RTC Config, they specify the errorReportingUrl by setting values in the \"url\" array as an object, instead of a string, e.g.:\n\n```html\n| Callout 1: `https://www.vendor1.com/foo?slot_id=1234`\n \nCallout 2: `https://www.vendor1.com/foo?slot_id=1234`\n | \n
| Not allowed\n | \n
| Callout 1: `https://www.vendor1.com/foo?slot_id=1234`\n \nCallout 2: `https://www.vendor1.com/foo?slot_id=5678`\n | \n
| Allowed\n | \n