nondeclared

Nondeclared is an adjective meaning not declared or defined within a given context, such as a software program, data format, or specification. In computing, nondeclared identifiers are names used in code without a prior declaration in the current scope, and the treatment of such identifiers depends on the language rules. In statically typed languages, using a nondeclared variable typically yields a compile-time error. In dynamically typed languages, outcomes vary: JavaScript in non-strict mode may create a global variable when assigning to a nondeclared identifier, leading to subtle bugs; in modern JavaScript with strict mode, referencing a nondeclared identifier raises an exception. C and C++, by contrast, require declarations for all identifiers and treat nondeclared usage as an error during compilation.

In data and configuration formats, an item is nondeclared if it is not defined in a schema, DTD, or schema-like specification. Parsers may ignore nondeclared fields, reject them, or be configured to accept them in a lenient mode. In XML, validating processors reject nondeclared elements or attributes, while non-validating processors might permit them. In JSON data, nondeclared keys can appear when schemas or validators are not used, affecting data quality and interoperability.

The term is also used descriptively to denote information that has not been officially announced or disclosed, such as nondeclared policy details in some organizational contexts. See also: undeclared variable, implicit declaration, declaration, strict mode, schema validation.