namespace Test.ServiceModel
open System
open System.IO
open System.Collections
open System.Collections.Generic
open System.Runtime.Serialization
open ServiceStack
open ServiceStack.DataAnnotations
    [<AllowNullLiteral>]
    type HelloDateTime() = 
        member val DateTime:DateTime = new DateTime() with get,set
To override the Content-type in your clients, use the HTTP Accept Header, append the .csv suffix or ?format=csv
The following are sample HTTP requests and responses. The placeholders shown need to be replaced with actual values.
POST /csv/reply/HelloDateTime HTTP/1.1 
Host: test.servicestack.net 
Accept: text/csv
Content-Type: text/csv
Content-Length: length
{"dateTime":"\/Date(-62135596800000-0000)\/"}
HTTP/1.1 200 OK
Content-Type: text/csv
Content-Length: length
{"dateTime":"\/Date(-62135596800000-0000)\/"}