XER stands for “XML Encoding Rules”, a form of XML specified in the X.693 standard for use with ASN.1.

NOTE: XER is maintained as a legacy XML format for ASN.1. New applications should consider using XML as described in the next section instead of XER. XML is more closely aligned with W3C standard XML and XML schema.

XER C encode functions are generated when the -xer switch is specified on the command line. For each ASN.1 prouction defined in the ASN.1 source file, a C XER encode function is generated. This function will convert a populated C variable of the given type into an XER encoded ASN.1 message (i.e. an XML document).

If C++ code generation is specified, a control class is generated that contains an Encode method that wraps this function. This function is invoked through the class interface to encode an ASN.1 message into the variable referenced in the msgData component of the class.