Input of placeholder tree into ARB. Sequences were exported from XplorSeq using the "Placeholder Tree" option. Sequences were split into two categories on the basis of associated meta-data (in this example, results of a PCR screen). Here, the user has selected all taxa belonging to the "neg" group. Because ARB propagates taxa markings between trees, placeholder trees can be used to graphically organize and manipulate groups of sequences that aren't necessarily related.
Frank BMC Bioinformatics 2008 9:420 doi:10.1186/1471-2105-9-420