It seems to be a visualization of *ABNF*, which is used in the JSON RFC (and other RFC's): https://www.ietf.org/rfc/rfc4234.txt.
– Felix KlingApr 06 '13 at 18:01
1
To be fair, I added the image. Maybe it was too much editing from my side, but since the OP explicitly referred to the website, I figured he meant those images. Please correct me if I'm wrong.
– Felix KlingApr 06 '13 at 18:03
exact duplicate of: http://programmers.stackexchange.com/questions/179801/how-are-json-org-like-specs-graphs-called-and-how-can-i-generate-them also look here http://stackoverflow.com/questions/796824/tool-for-generating-railroad-diagram-used-on-json-org
– AsafApr 06 '13 at 18:10