The input gene list can be either unordered or ordered. By default, the list is considered unordered and complete. If there exists some natural ranking of the genes, the ordered gene list option can be used. For example, the fold change in between different biological conditions, the number of neighboring nodes in a protein-protein interaction network, the absolute expression values or any other information relevant for the experimental setup could be a good basis for such ranking. In such cases the hypergeometric testing is performed for each possible prefix of the list starting from the first gene and adding next genes one by one. The smallest enrichment P-value is reported for each of the terms along with corresponding gene list length. For different terms this length can vary, especially as the broader terms can be enriched for larger lists only.
