Sugar-Version unknown

I am looking a detailed technical documentation for Spice-CRM. Additionally I will read the sugar documentation.
What means “sugar_version”: “2016.12.00”?
Is it based on SugarCRM 6.5 or 7.8?

Detailed Documentation is not available yet.
2016.12.00 means version published in December 2016 built 0.
If we had published next version in December 2016 we would have 2016.12.01
Latest version is 2018.01.00

SpiceCRM is based SugarCE 6.5.22