WITSML - survey program schema The WITSML API mandated plural root element which allows multiple singular objects to be sent. The plural name is formed by adding an "s" to the singular name. Information about the XML message instance. A single survey program . Data object schema version. The fourth level must match the version of the schema constraints (enumerations and XML loader files) that are assumed by the document instance. Human recognizable context for the well that contains the wellbore. Human recognizable context for the wellbore that contains the survey program. Human recognizable context for the survey program. The non-contextual elements for a survey program. A container element that contains elements that are common to all data objects. A container element that can contain custom or user defined data elements. Unique identifier for the well. This uniquely represents the well referenced by the (possibly non-unique) nameWell. Unique identifier for the wellbore. This uniquely represents the wellbore referenced by the (possibly non-unique) nameWellbore. Unique indentifier for the survey program.