Which segment is used to transmit fields common to all types of orders requested?

The ORC Segment, which stands for Order Control Segment, is used to transmit fields that are common to all types of orders requested in HL7 messaging. This segment provides essential information related to the order, such as order control codes, order status, and other details necessary for managing the order across various systems.

By being a standardized segment applicable to different types of orders, the ORC segment ensures consistency in the way order-related information is communicated within healthcare environments. It serves as a foundational component that supports the various types of orders, which can include laboratory tests, medication orders, and other clinical requests.

In contrast, other segments like the OBR Segment are specific to observation requests and contain detailed results of specific observations. The ERR Segment is used for error reporting and conveys messages related to issues encountered in processing other segments, and the Order entry segment is not a standard HL7 segment terminology used for transmitting common order fields. Thus, the ORC segment stands as the correct answer due to its wide applicability in transmitting order information universally across healthcare systems.