Constructor.
The original HED string.
The nested list of parsed HED tags, groups, and column splices.
All the column splices in the string at all levels.
The top-level definition tag groups in the string.
The original HED string.
The normalized string representation of this HED string.
The parsed substring data in unfiltered form.
The tag groups in the string (top-level).
All the tags in the string at all levels.
The tags in the top-level tag groups in the string.
All the top-level tags in the string.
A parsed HED string.