programming languages, each with varying levels of conformance. The standard filename extension is .json. The JSON standard does not support object references, but an IETF draft standard for JSON-based object references exists. Uses JSON-RPC is a remote procedure call (RPC) protocol built on JSON, as a replacement for XML-RPC or SOAP. It is a simple protocol that defines only a handful of data types and commands. JSON-RPC lets a system send notifications (information to the server that does not require a response) and multiple calls to the server that can be answered out of order. Asynchronous JavaScript and JSON (or AJAJ) refers to the same dynamic web page methodology as Ajax, but instead of XML, JSON is the data format. AJAJ is a web development technique that provides for the ability of a webpage to request new data after it has loaded into the web browser. Typically it renders new data from the server in response to user actions on that webpage. For example, what the user types into a search box, client-side code then sends to the server, which immediately responds with a drop-down list of matching database items. While JSON is a data serialization format, it has seen ad hoc usage as a configuration language. In this use case, support for comments and other features have been deemed useful, which has led to several nonstandard JSON supersets being created. Among them are HJSON, HOCON, and JSON5 (which despite its name, is not the fifth version of JSON). The primary objective of version 1.2 of YAML was to make the nonstandard format a strict JSON superset. In 2012, Douglas Crockford had this to say about comments in JSON when used as a configuration language: "I know that the lack of comments makes some people sad, but it shouldn't. Suppose you are using JSON to keep configuration files, which you would like to annotate. Go ahead and insert all the comments you like. Then pipe it through JSMin before handing it to your JSON parser." JSON is intended as a data serialization format. However, its design as a subset of JavaScript can lead to the misconception that it is safe to pass JSON texts to the JavaScript function. This is not safe, due to certain valid JSON texts, specifically those containing or , not being valid JavaScript code until JavaScript specifications were updated in 2019, and so older engines may