[TAG_EXTENSION_INVALID] tag-extension-invalid-bad-node-name not detected

[VisLab]

The specification now has a restriction for node names as being from the nameClass:

alphanumeric, blank, hyphen, period, underscore, nonascii.

This accommodates the UTF-8 but is still restrictive see A.1.3. Value classes.

There currently don't seem to be any checks on the validity of tag extensions.

Example: Red/Red$ish should be invalid but is not.