[x3d-public] appinfo attribute/field

[Michalis Kamburelis]

Let me add another question to this thread: Where is the specification
of how to *encode* appinfo information in the X3D classic encoding?

To add some background/context to this question:

- Thanks to John pointing out in
https://github.com/castle-engine/castle-engine/issues/688 , in CGE we
lack support for "appinfo" attribute in ProtoDeclare / field.

- I found a mention of new "appinfo" and "documentation" in the
abstract X3D 4.0 spec:
https://www.web3d.org/documents/specifications/19775-1/V4.0/Part01/concepts.html#PROTOinterfacedeclsemantics
,"""Prototype and field declarations may optionally include appinfo
functional descriptions (i.e., tooltip summary) and a documentation
url providing a link to further related information."""

- However, as the above is the "abstract" part of the spec ("X3D
Abstract : Architecture and base components") so it naturally doesn't
say how these "appinfo" and "documentation" are actually encoded. The
official XML encoding and classic encoding specs are now at 3.3
version -- so they don't mention how to encode this new X3D 4.0
feature.

- For XML encoding, it seems straightforward, judging from the
testcase in https://github.com/castle-engine/castle-engine/issues/688
. They are just XML attributes.

    <ProtoDeclare appinfo='...' name='...' ...>

    <field appinfo='...' ...>'

    OK, so XML encoding is simple enough:)

- We need to know how to encode this information in X3D classic, to
enable lossless conversion between X3D encodings (classic, XML etc.).

- If there is a spec, and/or a clear example of how to do this in X3D
classic encoding, please point me to it :) Thank you!

Regards,
Michalis