Systems and methods are provided allowing for a vendor-defined payload in a standardized user-plane location solution/protocol, where proprietary extension support is introduced into one or more standardized solutions. In accordance with a first embodiment, a location payload consists of structures for transferring requests, assistance data, measurements and positioning instructions. Therefore, a proprietary extension is included in each of these structures so that, for example, proprietary assistance data can be requested in an appropriate structure. In accordance with another embodiment, a proprietary extension is introduced at the highest abstraction level. For example and in an actual implementation, a vendor can define that in the beginning of the proprietary payload, the proprietary extension is defined, whether the proprietary payload contains a request, assistance, etc.