Thank you for clarifying your use case.
Using field "Primary Trading RIC" in a T&C (Terms And Conditions) request seems fine to me.
I made some T&C tests with UNP, trying to request the primary trading RIC from RICs UNP.F, UNP.N, UNP, and ISIN US9078181081, In all 4 cases I receive UNP.N as the primary trading RIC.
After investigating with a data specialist, he told me that UNP.N (on NYS) is the primary RIC, whereas UNP (on NYQ) is a consolidated quote, not the primary RIC. This can be seen in Eikon, using a search for UNP:
The Eikon quote displays different venues for Bid and Ask, which also hints at a consolidated RIC:
I am a bit confused about where you see in Eikon that the "Primary RIC" is "UNP", I could not reproduce that.
Added 14 Nov, from other answers / comments, to summarize all info in one place:
Note also that most equity RICs in Elektron carry a specific RIC code in field 728 (BCAST_REF) (used to retrieve NEWS), which should be the Primary RIC. For UNP, UNP.F and UNP.N it contains UNP.N, confirming that UNP.N is the primary.
From what you observe, we must conclude that the primary RIC displayed under Codes and Schemes from the Corporate Information screen in Eikon is not always reliable.
As a final conclusion, I'd use field "Primary Trading RIC" from a T&C request, it delivers the correct information.
I am guessing you are starting with an ISIN, Cusip or Sedol.
For C# code using the .Net SDK, this is explained in detail in the .Net SDK tutorial 8, which is also delivered as downloadable code.
All it takes is to use a set of ISINs as input, and the returned RIC will be the primary.
Thanks for your response.
I am strting with RIC. Its because I want to find out the "Primary RIC" of an existing "RIC".
e.g Primary RIC code of UNP.N is UNP
I tried using Terms And Conditions request but "Primary Trading RIC" is coming "UNP.N" instead of "UNP". When I search for "UNP.N" in Eikon I can see "Primary RIC" is "UNP".
Can you please advise how to retrieve "Primary RIC" from "RIC"
Here is the screen shot in Eikon
When I try using Terms And Conditions Request API "Primary Trading RIC" is coming "UNP.N" instead of "UNP".
Please advise how I can retrieve Primary RIC from .net SDK REST APIs.