Looking at the images under Syntax here.

It shows the syntax (grammar) in a visual way. Is there specialized software for creating and editing such diagrams?
Looking at the images under Syntax here.

It shows the syntax (grammar) in a visual way. Is there specialized software for creating and editing such diagrams?
SQLite's railroad diagrams are rendered using a diagramming tool made by SQLite's author: Pikchr.
Some web searching for "syntax diagram generator" (and similar phrases) got me this: http://karmin.ch/ebnf/index
I've never used it but it looks like it will generate syntax diagrams. They won't look 100% like Oracle's but they should still be usable. I don't know what tool Oracles, uses. Probably some internal tool that they don't distribute.
Here's another one:
See Tool for generating railroad diagram on StackOverflow.
There is an online railroad diagram generator which generates SVG diagrams from EBNF
