I can export and import global list with witadmin.
witadmin exportgloballist /collection:http://imtfs:8080/tfs/DefaultCollection /f:c:\temp\globallist.xml
witadmin importgloballist /collection:http://imtfs:8080/tfs/DefaultCollection /f:c:\temp\globallist.xml
Can I do the same by code? Can I do it by C# with Microsoft.TeamFoundationServer.Client? Can I do it with REST?
Yes, you can use REST API: https://learn.microsoft.com/en-us/rest/api/azure/devops/processes/lists?view=azure-devops-rest-6.0
Or Team foundation Client:
WorkItemTrackingProcessHttpClient ProcessHttpClient = Connection.GetClient<WorkItemTrackingProcessHttpClient>();
var lists = ProcessHttpClient.GetListsMetadataAsync().Result;
var list = ProcessHttpClient.GetListAsync(lists[1].Id).Result;
list.Items.Add("PREPROD");
var updatedList = ProcessHttpClient.UpdateListAsync(list, list.Id).Result;
The result:
