Home | Blog | HL7 & Interoperability | HL7 ORC Segment Structure, Standards, And Best Practices

HL7 ORC Segment Structure, Standards, And Best Practices

Reading time: 12 minutes

HL7 (Health Level Seven) is a messaging standard for exchanging or transferring healthcare information between disparate healthcare systems in an organization. The messages are made up of a set of delimited fields called segments. These segments are stored on a single line and describe the subject part of a message. These subject parts include PID (a patient), ORC (an order), and the message header (MSH). 

What is the HL7 OCR Segment?

An OCR segment or otherwise known as, The Common Order Segment, is used to transmit fields that are all types of services that are requested or all the common orders. The common order segment (ORC) is mandatory in the Order message (ORM) and the Order Acknowledgement (ORR) messages (If the order detail segment is present). If the details are needed for a particular type o order segment, such as laboratory, pharmacy, or dietary, the ORC then must start any order detail segment (e.g., ODS, RXO). In some instances, the Common Order Segment may be a simple string.

An example of a simple ORC string: ORC│OK│<placer order number>│<order status>│<cr>.

If details (such as time and date) are not needed for the order being transmitted, the order detail segment of the string may be excluded. For example, If a medical professional needs to place an order on hold, an ORC would be transmitted with the following fields completed: ORC-1-order control with a value of HD, ORC-2-placer order number, and the final field, ORC-3-filler order number. 

There are overlaps between fields in the order of detail segments and fields of the ORC.

Overlaps Between Fields Of The OCR And Those In The Order Detail Segments

Place Order Groups

The HL7 messaging standard supports a mechanism to collect and group several orders together. This grouping of several orders together is represented as an “ordering session” for a single patient. An order group is a listing of Common Order Segments that are associated with an OCR-4-placer group number. A group is only created when the placer provides a placer group number with the original order logged. The order group is made up of all the order detail segments and ORCs that have the same placer group number. New orders can only be added using parent-child or replacement mechanisms, and new orders can be deleted using cancel.

Duplicate Fields

The role of the OCR is to uniformly describe the fields that are common to all requested services (orders). Some of the OCR fields are duplicated in some order detail segments in the message. For example, the OBR-2-placer order number has the same purpose and meaning as the ORC-2-placer order number. Duplicate fields promote compatibility upward with past versions of HL7 and ASTM. When using duplicate fields, the rule of thumb is that if a value does not appear in the OCR, then it must appear in the order detail segment. It is thus recommended to transmit/send the field value in both OCR and the duplicate field to avoid any confusion.  

Parent/Child – Cancel, Hold, Discontinue

For example:

  • An ECG application receives an order for five ECGs on consecutive afternoons.
  • The ECG application then creates five child orders, one for each ECG request.
  • The first afternoon ECG has already occurred when a request is received to cancel the original parent order of five ECGs. The parent order is beyond the point of cancellation n.
  • Thus, the remaining children (orders) that have been unperformed are canceled as a result of the request in point 3.

ORC Field Definitions

There are 21 OCR fields; below, we discuss the fields and their definitions.
ORC-1 Order Control: This determines the function of the order segment.

OCR-2 Placer Order number: is the field of the placer application’s order number, with the components; ^ ^

ORC-3 Filler order number: This field is the order number that is associated with the filling application, with the following components: 6 ^ .

ORC-4 Placer group number: This field grants an order placing application to group a set(s) of orders together and identify them. This OCR field is an example of an EI- Entity Identifier data type.  

ORC-5 Order Status: This field designates the status of an order that has been made.

ORC-6 Response flag: This field lets the sending (placer) application to establish the amount of information to be returned from the filler.

ORC-7 Quantity/timing: This field specifies the frequency, quantity, timing, and priority of an atomic service.

ORC-8 Parent: This field associates a child to its parent order when there is a parent-child relationship.  

ORC-9 Date/time of the transaction: The date and time the order is initiated are shown in this field.

ORC-10 Entered by (XCN): this field encloses the identity of the person that keyed in the request/order.

ORC-11 Verified by (XCN): This field encloses the identity of the person who verified the request/order.

ORC-12 Ordering provider: This field encloses the identity of the person who is responsible for creating the order/request.

Other OCR fields include:

ORC-13 Enterer’s location
ORC-14 Call back phone number
ORC-15 Order effective date/time
ORC-16 Order control code reason
ORC-17 Entering organization
ORC-18 Entering device
ORC-19 Action by (XCN)
ORC-20 Advanced beneficiary notice code 
ORC-21 Ordering facility name 
ORC- 22 ordering facility address
ORC- 23 Ordering facility phone number
ORC-24 Ordering provider address 
ORC-25 Order status modifier 
ORC-26 Advanced beneficiary notice override reason
ORC-27 Filler’s expected availability Date/Time
ORC-28 Confidentiality code
ORC-29 Order Type 
ORC-30 Enterer Authorization mode


The ORC is where the message order details are held, with patient orders classified as New Orders, ORC fields also contain information about the order number for the filling system, from the source system, and the date and time the order was created. Thus, these fields provide vital information that gets transferred in HL7 messages across healthcare systems.

Did you find The Common Order Segment of HL7 messaging interesting and would like to read more about the services we offer healthcare businesses? Check out our blog or service page to see how we can help you.

Share On:

Leave a Reply

Your email address will not be published. Required fields are marked *