The hevc/h265 documentation is an important standard becauseCodeSometimes it is modified due to efficiency issues, which is the most important reference:
Hevc approved by ITU-T and ISO/IEC
"Geneva, 25 January 2013- A
New video coding standard building on the Primetime Emmy award winning ITU-T H.264/MPEG-4 AVC was agreed by ITU members today".
The ITU-T has announced approval of the new high efficiency video coding (hevc) standard. The new standard will be co-published as recommendation ITU-T h.265 and ISO/IEC 23008-2.
Hevc is intended to be a successor to the popular H. 264/advanced video coding standard, first published in 2003. as with every video coding standard, the performance of hevc depends on the way it is put into practice. the developers of the standard, a consortium
Of ITU-T VCEG and iso mpeg known as the joint collaborative team on video coding, are expecting hevc codecs to offer around twice the compression efficiency of H. 264/AVC. that means approximately half the bandwidth for the same video quality.
You can download a draft of the hevc standard and the reference software codec here.