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# format described in ../help.readme


TITLE		Trees

OCCURRENCE	ARB_NT

DESCRIPTION	A tree consists of two types of 'nodes':

		- tips or terminal nodes: species

			connected to exactly one father

		- inner nodes: hypothetical ancestors

			connected to one father
			(and in the binary case to two children).
			A group_name may be assigned to an inner node; in this
			case, the node and all its children become a group.
			<ARB_NT/INFO_MODE/M>

		There are significant differences between
		phylogenetic trees and binary trees:

		phylogenetic trees 		 	binary trees:
                -------------------------------------------------------------------------
		unrooted				rooted
		inner nodes have n children		all inner nodes have two children

		Since binary trees are much easier to handle, ARB converts
		phylogenetic trees to binary trees.