In MarvinSpace any visible element can be labeled. Though from the gui only named components can be labeled such as atoms, residues, molecules and secondary structures. The labels can be colored to enhance visibility.
Labels on selection is an other way of displaying labels on a visible element by selection. In case of selecting atoms, if this box is checked the residue atom label of the selected atoms are displayed next to the atom. The residue atom label consists of the residue name (3 letter abbreviation in the case of amino acids, or 1 letter code in the case of nucleic acids), the residue sequence number, the chain identifier and the atom label.