A string optionally followed by a positive integer enclosed in matching parentheses. The first example denotes the first occurrence of a vertex named foo , while the second form denotes the 33rd occurrence of a vertex named bar . A positive integer. These denote the vertex whose rank is the specified number. The first vertex's rank in a node is 1, the second 2, and so on.
Many operations use an insert order specifier.
Some insert order specifiers are followed by a rank specifier, a positive integer, to determine an absolute position. This insert order specifier is not followed by a rank specifier. The newly inserted vertex becomes the last in this node. This insert order specifier is not followed by a rank specifier. Must be followed by a rank specifier.