VRML97 and ClassicVRML encodings use the term PROTO, while XML and JSON encodings use the ProtoDeclare element.

ProtoDeclare is a Prototype Declaration, defining a new node made up of other node(s). ProtoDeclare contains ProtoInterface and ProtoBody statements. Hint: ProtoDeclare is a definition only, add corresponding ProtoInstance nodes to create new instances.

VRML97 and ClassicVRML encodings simply uses the prototype name, while XML and JSON encodings use the ProtoInstance element.

ProtoInstance creates an instance node of a locally or externally declared prototype definition. ProtoDeclare/ExternProtoDeclare definitions are abstract, corresponding ProtoInstance nodes are concrete. ProtoInstance nodes typically contain fieldValue statements to override default field values defined in the original ProtoDeclare statement. Hint: the node type of a ProtoInstance exactly matches the first node in the corresponding ProtoDeclare/ProtoBody declaration.

X3D Tooltips of interest: ExternProtoDeclare statement, ProtoDeclare statement, ProtoInterface statement, ProtoBody statement, field, IS, connect, and ProtoInstance node with fieldValue statement.

X3D Specification sections of interest: Core component, 7.2 Concepts and 7.2.5.8 PROTO statement.

X3D Examples Archives of related interest:

• VRML 2 Sourcebook:  Chapter 31 Prototypes
• X3D for Web Authors: Chapter 14 Prototypes

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