SharePoint 2010 REST Date/Time format

Question

In SharePoint 2010 REST API when I call to _vti_bin/ListData.svc/Documents(38)/Created and get JSON response the date/time is returned as /Date(1421146908000)/ (I found some information about it but not still sure what this number counts and from which epoch). But when I get actual value calling to _vti_bin/ListData.svc/Documents(38)/Created/$value, I get Edm.DateTime value 2015-01-13T11:01:48.

Does anyone know

1. Is it always the case I can rely on? The reason is that I use actually _vti_bin/ListData.svc/ service of SP 2013 server (since I don't have SP 2010).
2. Is there some official information about date/time formats returned in different cases?
3. Is it really Edm.DateTime or may be Edm.DateTimeOffset?

Thanks a lot!

Answer 1

According to the protocol specification document Edm.DateTime (VJsonDateTime) has the following JSON format:

VJsonDateTime= quotation-mark  
              "\/Date(" 
              ticks
              [("+" / "-") offset]
              ")\/" 
              quotation-mark 

ticks       = *DIGIT 

; ticks is the number of milliseconds since midnight  
; January 1, 1970 

offset      = 4DIGIT
; offset represents the number of minutes to add (if preceded by "+") or substract
(if preceded by "-") from the time value represented by ticks
; if no offset is specified, the value MUST be interpreted as UTC.

;Note: This format is the same used by the ASP.NET 
;AJAX framework, described in http://msdn2.microsoft.com/en-;us/library/bb299886.aspx

From another hand, the document states that DateTimeOffset in JSON should follow the same format as the Date in JSON :

VJsonDateTimeOffset =  VJsonDateTime