Table 1.

Attributes assigned to genomic features

Key	Value	Usage
Evidence_code	icw(n)	FIG term: in cluster with; indicates that the PEG occurs in a cluster with n other genes from the same subsystem (very strong evidence)
	isu	FIG term: in subsystem unique; indicates that the PEG occurs in a subsystem, and it is the only PEG for that genome that has been assigned the functional role (i.e. the cell in the spreadsheet contains a single entry)
	idu(n)	FIG term: in subsystem duplicates; indicates that the PEG occurs in a subsystem, but it is in a cell of the spreadsheet containing duplicates
	TAS	GO term: traceable author statement
Structure	Stuctural_classification_projected from_homologous_protein_in_E._coli	Link to relevant entry in SCOP: Structural Classification of Proteins (http://scop.mrc-lmb.cam.ac.uk/scop/)
PubMed	PMID number	Link to published abstract in PubMed
SA_essential_Ji	Essential	Function for S.aureus protein in experiment by Ji et al. (22)
	Potential_essential	Function for S.aureus protein in experiment by Ji et al.
	Undetermined	Function for S.aureus protein in experiment by Ji et al.

This is a partial list of the most common attributes in the form of key-value pairs. The Usage column gives a brief description of the attribute, or provides a link to the relevant source.