Set the UNSEALED attribute of the numth node to "true" or "false".
setunsealed(num, bool_str)
A path of unsealed nodes in the parse tree can be searched via the @NODES selector. If a node is sealed, then @NODES won't look inside it. Another way is with the element modifier unsealed. The code below places the unsealed attribute on a _sentence node.
@RULES
_sentence [unsealed] <- _np _vp @@
@POST
setunsealed(1,"true"); # Allows _sentence nodes to be examined by a subsequent pass that uses @NODES.
@RULES
_xNIL <- _sentence @@