multiname

Multiname is a term used in certain programming runtimes to describe an identifier that can reference a symbol through one of several namespaces (or a set of namespaces). It is most widely associated with the ActionScript 3 runtime (AVM2) and the SWF file format, where property and method names are stored as multinames rather than simple strings. This design supports the language’s namespace and access-control features and enables dynamic dispatch across multiple namespaces.

In this model, a multiname encodes both a local name and a namespace qualifier, or a collection of possible namespaces. The most common forms are QName, a qualified name consisting of a single specific namespace and a local name; Multiname, a name that may be associated with several namespaces; and runtime forms such as RTQName or RTQNameL, where the exact namespace or name may be resolved at runtime, enabling dynamic property access.

At compile time, multinames are used in the ABC (ActionScript Byte Code) metadata to map references to the actual runtime objects. At run time, the AVM2 uses the multiname to resolve which property to access based on the invoked context and the namespaces present on the target object, supporting features like namespace-based access control and dynamic member lookup.

Beyond ActionScript, the concept of a name qualified by a namespace appears in other systems that support namespaces, though the explicit term multiname is most closely tied to AVM2 and the SWF ecosystem.