Part of SpreadON's design philosophy is to completely avoid the guess-work of YAML, by explicitly declaring the data type as a type name tag. This also enables extension tags for other formats and features like grids of identically typed data, sheet and named region references, etc. And also to avoid the inconvenient syntax of JSON as much as possible.

It addresses the most-complained-about problems with JavaScript: no comments, and no trailing commas. You can use the unused cells to the right as comments (or even intermediate calculation formulas), and not only is there no inconsistency about not being able to put a comma after the last element of an array or object, but it actually doesn't require any commas at all, no quotation marks around string, no backslashes in strings, no spaces or tabs for indentation, nor any other syntactic syrup of ipecac that JSON requires but YAML foolishly tries to avoid by guessing. Each cell is a separate syntactic token, so you don't need commas or spaces or tabs to separate them.