Hi @Lorenzo Scalese ! Yes! It is in Location header, as @Tani Frankel mentioned. 

This is what I received in headers:

http://localhost:52773/fhir/r4/Patient//1983/_history/1
So, the id is 1983.

It is a bit different from what the public FHIR server on hl7.org/fhir returns - it returns the id also in a response.

Not sure though what is the "standard" behavior but if find it convenient enough to have the id in the response.  

Was able to install with Brew:

$ brew install caretdev/tap/irissqlcli

AEMBP14ESHVAROV:~ eshvarov$ irissqlcli -h localhost -p 1972 -u _SYSTEM -W

Password for _SYSTEM: 

Server:  InterSystems IRIS Version 2022.2.0.368 xDBC Protocol Version 65

Version: 0.4.0

[SQL]_SYSTEM@localhost:USER> 

select 1

+-----------+

| HostVar_1 |

+-----------+

| 1         |

+-----------+

1 row in set

Time: 0.044s

Amazing. 

Thank you @Dmitry Maslennikov