Meaning of $ in key name

[Json Schema]

$schema
$ref

What is the reason for the 4 symbol? Is it signifying they reference
other schemas? Or that something external to the schema is being
referenced?

[Francis Galiegue]

The $ is a character like any other in a JSON string. I guess it has
been picked as special for convenience...

It should be noted though that:

{
"$ref": "whateverurihere"
}

can be viewed as a JSON Reference, which is specified (don't have the
link handy atm).

--
Francis Galiegue, fgal...@gmail.com
"It seems obvious [...] that at least some 'business intelligence'
tools invest so much intelligence on the business side that they have
nothing left for generating SQL queries" (Stéphane Faroult, in "The
Art of SQL", ISBN 0-596-00894-5)