<tree>

<tree> codifica un árbol, que se constituye de raíz, nodos internos, hojas, y arcos que conectan raíz y hojas. 19.2 Trees
Módulonets — 19 Graphs, Networks, and Trees
Atributos
arityestablece el número máximo de hijos (descendientes) de la raíz y de los nodos internos del árbol.
Estado Opcional
Tipo de datos 
data.count
Valores A nonnegative integer.
ord (ordered) indica si el árbol es o no ordenado, o si es parcialmente ordenado.
Estado Necesario
Los valores admitidos son:
true
indicates that all of the branching nodes of the tree are ordered. [Por defecto]
partial
indicates that some of the branching nodes of the tree are ordered and some are unordered.
false
indicates that all of the branching nodes of the tree are unordered.
orderproporciona el orden del árbol, es decir, el número de los nodos.
Estado Opcional
Tipo de datos 
data.count
Valores A nonnegative integer.
Nota
The size of a tree is always one less than its order, hence there is no need for both a size and order attribute.
Used byforest model.divPart
May contain
core: label
nets: iNode leaf root
Declaración
element tree
{
   att.global.attributes,
   attribute arity { data.count }?,
   attribute ord { "true" | "partial" | "false" },
   attribute order { data.count }?,
   ( label?, ( ( leaf | iNode )*, root, ( leaf | iNode )* ) )
}
Ejemplo
<tree
  n="ex2"
  arity="2"
  ord="partial"
  order="13">
 <root xml:id="G-div1" children="#G-plu1 #G-exp1" ord="true">
  <label>/</label>
 </root>
 <iNode
   xml:id="G-plu1"
   children="#G-exp2 #G-exp3"
   parent="#G-div1"
   ord="false">
  <label>+</label>
 </iNode>
 <iNode
   xml:id="G-exp1"
   children="#G-plu2 #G-num2.3"
   parent="#G-div1"
   ord="true">
  <label>**</label>
 </iNode>
 <iNode
   xml:id="G-exp2"
   children="#G-vara1 #G-num2.1"
   parent="#G-plu1"
   ord="true">
  <label>**</label>
 </iNode>
 <iNode
   xml:id="G-exp3"
   children="#G-varb1 #G-num2.2"
   parent="#G-plu1"
   ord="true">
  <label>**</label>
 </iNode>
 <iNode
   xml:id="G-plu2"
   children="#G-vara2 #G-varb2"
   parent="#G-exp1"
   ord="false">
  <label>+</label>
 </iNode>
 <leaf xml:id="G-vara1" parent="#G-exp2">
  <label>a</label>
 </leaf>
 <leaf xml:id="G-num2.1" parent="#G-exp2">
  <label>2</label>
 </leaf>
 <leaf xml:id="G-varb1" parent="#G-exp3">
  <label>b</label>
 </leaf>
 <leaf xml:id="G-num2.2" parent="#G-exp3">
  <label>2</label>
 </leaf>
 <leaf xml:id="G-vara2" parent="#G-plu2">
  <label>a</label>
 </leaf>
 <leaf xml:id="G-varb2" parent="#G-plu2">
  <label>b</label>
 </leaf>
 <leaf xml:id="G-num2.3" parent="#G-exp1">
  <label>2</label>
 </leaf>
</tree>
Nota
A root, and zero or more internal nodes and leaves, but if there is an internal node, there must also be at least one leaf.