What functional changes are there between VRML97 and X3D?
There are many subtle and not so subtle changes. It would be impossible to list them all, but here are a few of the bigger ticket items that you need to be aware of: • Files are now structured to define the required capabilities as part of the header. This requires at least a definition of a profile and any extra components. • Externprotos now only define external X3D file content. They cannot be used to provide extension mechanisms to browsers. The way to provide browser-specific extensions is through custom components. • Access names for fields have changed from eventIn, eventOut, field and exposedField, to inputOnly, outputOnly, initializeOnly and inputOutput, respectively. • Scripts can have inputOutput fields (exposedFields) defined • A DEF name is not allowed to be multiply defined any more • All loading of content is lazy loading. Where VRML97 would require that scripts must be loaded before the runtime can start, X3D removes this and states that the file runtime starts running
