Updated 6/15/2026

Although the DirectTrust Aggregated Directory is represented in a flat Comma Separated Values (CSV) file, the Aggregated Directory contains valuable hierarchical relationships that improve searchability for Direct addresses.

Similar to how a cotter pin in an engine prevents nuts and bolts from loosening or falling out due to high vibrations, the ORG_UID field holds information together for a single facility in a Directory CSV contribution file. The ORG_UID field is the part that makes it possible for multiple flat file entry rows to stay connected as a hierarchical representation of the information about the healthcare facility and the facility’s provider personnel, which makes it possible to find Direct addresses when they are needed.

Each Direct address contributed to the Aggregated Directory is supplied with details about the organization’s facility locations and individual providers who are able to receive information via the contributed Direct addresses. The practice location and provider information is contributed to the DirectTrust Directory to improve Direct address searchability.

The Aggregated Directory Service enables HISPs to assign or use identifiers for each verified organization and its verified practice locations where care is delivered. The unique identifiers assigned by the HISP for each practice location can be contributed to the Directory in the field called ORG_UID where ORG_GEO_ADDR_TYPE is “practice.” 

When a vendor integrator includes Direct services as part of their solution, the HISP and that vendor must agree on how each verified location will be assigned an ORG_UID identifier. For example, the vendor may assign a unique facility ID and then the HISP may prepend that ID with an identifier established for the organization. 

Directory Best Practices Note – Include Unique Identifiers

As of the Directory Services User Guide v2.8, best practice guidance has been for HISPs to include provider and practice location identifiers in the Directory CSV contribution file. Although relying on the Aggregated Directory Service to assign identifiers is still supported, in the future, verified legal entity identifiers will likely be used to ensure proper hierarchical representation of the Directory Data.

ORG_UID appears on every row in the CSV contribution file where Direct address information is associated with that specific practice location or where practitioner information is associated with that specific practice location. When the Directory contributions are aggregated, the HISP identifier (HISPID) field is appended to the ORG_UID so that every single practice location in the DirectTrust Aggregated Directory has a unique identifier. Facilities that use Direct services from two different HISPs can, in this way, be differentiated.

In the DirectTrust Aggregated Directory, the relationships between Direct address endpoints, practitioners, and practice locations are maintained despite the flat CSV file representation of this hierarchical data. Each row of the Directory CSV contribution file provides different parts of the hierarchically modeled directory information. It may require many rows of data to represent a single situation. The ORG_UID field holds multiple rows together for a single location.

For example, a healthcare organization with two locations and two different providers at each location would need a minimum of (4) row entries in the CSV file to contribute their Direct address information to the Aggregated Directory.

Example:

  1. The first two rows would contain the information for the first location, with each row including one of the providers and their Direct address. Each Direct address would be associated with the managing organization named in the associated X.509 certificate. 
  2. The next two CSV rows would contain information for the second practice location with one provider in each row and their associated Direct address.

In a more complex scenario, the organization could utilize workflow addresses at different locations in addition to, or in place of assigning individual provider addresses. Direct is not a one-size-fits-all solution, and as a result, the Aggregated Directory Data can look different for different organizations.

However, constructing a Directory CSV contribution file can be accomplished in a step-by-step process. 

First, it is essential to know what practice locations need to be included in the directory for each organization. Every row always includes location information by supplying a location name and practice address confirmed during the identity proofing process for the organization. (ORG_GEO_ADDR_TYPE = practice). 

Next, if an organization has any workflow addresses, each of those Direct addresses needs to be included in one row of the Directory CSV contribution file, associated with the relevant practice location. If the organization wants those workflow addresses to be used for certain use cases, the Direct address should be labeled with an appropriate “use case description” code called the Service Description using the SERV_DESC Directory Data Element.

Finally, personnel that need to be finable in the DirectTrust Aggregated Directory are added and associated to the location(s) where they provide care to patients. 

If the provider or employee is provisioned a Direct address for their individual use, that address can be included and marked with a Service Description of “individual-practitioner” or “individual-employee”. Direct addresses that support workflows benefiting multiple providers at one location can be marked with a Service Description of “referrals” or “event-notifications”.

If the facility’s workflow addresses are the only way providers receive information via Direct, the provider can simply be listed on a CSV row for their practice location. No individual Direct address needs to be included. This option ensures the provider can be found in the Directory at a specific practice location, and the available workflow addresses for that location can be identified to determine the correct Direct address to use.