and XML similarly do not require a schema, making them easy to use. They are also both cross-platform standards that are broadly popular for communications protocols, particularly when combined with a JSON schema or XML schema. Some ASN.1 tools are able to translate between ASN.1 and XML schema (XSD). The translation is standardised by the ITU. This makes it possible for a protocol to be defined in ASN.1, and also automatically in XSD. Thus it is possible (though perhaps ill-advised) to have in a project an XSD schema being compiled by ASN.1 tools producing source code that serializes objects to/from JSON wireformat. A more practical use is to permit other sub-projects to consume an XSD schema instead of an ASN.1 schema, perhaps suiting tools availability for the sub-projects language of choice, with XER used as the protocol wireformat. For more detail, see Comparison of data serialization formats. See also X.690 Information Object Class (ASN.1) Presentation layer References External links A Layman's Guide to a Subset of ASN.1, BER, and DER A good introduction for beginners ITU-T website - Introduction to ASN.1 A video introduction to ASN.1 ASN.1 Tutorial Tutorial on basic ASN.1 concepts ASN.1 Tutorial Tutorial on ASN.1 An open-source ASN.1->C++ compiler; Includes some ASN.1 specs., An on-line ASN.1->C++ Compiler ASN.1 decoder Allows decoding ASN.1 encoded messages into XML output. ASN.1 syntax checker and encoder/decoder Checks the syntax of an ASN.1 schema and encodes/decodes messages. ASN.1 encoder/decoder of 3GPP messages Encodes/decodes ASN.1 3GPP messages and allows easy editing of these messages. Free books about ASN.1 List of ASN.1 tools at IvmaiAsn project Overview of the Octet Encoding Rules (OER) Overview of the JSON Encoding Rules (JER) A Typescript node utility to parse and validate ASN.1 messages Data modeling languages Data serialization formats ITU-T X Series Recommendations