Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Look up table for mask_version.
| mask_version | Geographical mode mask version* | Date Period |
|---|---|---|
| 1 | 3.1 | November 2010 to 17 April 2011 |
| 2 | 3.2 | 18 April 2011 to 6 May 2012 |
| 3 | 3.3 | 7 May 2012 to 30 September 2012 |
| 4 | 3.4 | 1 October 2012 to 6 July 2014 |
| 5 | 3.5 | 7 July 2014 to 5 October 2014 |
| 6 | 3.6 | 6 October 2014 to 13 December 2015 |
| 7 | 3.7 | 14 December 2015 to 6 March 2016 |
| 8 | 3.8 | 7 March 2016 to 29 January 2017 |
| 9 | 3.9 | 30 January 2017 to 19 August 2019 |
| 10 | 4.0 | 19 August 2019 onwards |
