Tree Annotation Format for RRG Syntactic Structures
Since the standard data structure for treebank annotations is trees,
specifically, a single tree per sentence, we adopt a notational variant
for the RRG structures (exemplified in the right half of the picture
It departs from the usual representation of RRG structures (see the
left half of the figure) in several ways:
Since the spine of the operator projection mirrors the
spine of the constituent projection, we identify the
corresponding nodes (for example, CLAUSE, CORE, NUC and V) and
attach operators in the same tree as other constituents.
We represent arrows as ordinary edges (and eliminate
PERIPHERY nodes). The roots of operators, peripheries and
clause linkage markers become daughters of the noes they attach
to (see the TNS, CLM and AP nodes in the example).
In order to still distinguish operators and peripheries, we
decorate the labels of their roots with -OP and -PERI,
respectively. Clause linkage markers are already distinguished
by the root label CLM.