RasMol atom expressions may contain predefined sets. These sets are single keywords that represent portions of a molecule of interest. Predefined sets are often abbreviations primitive atom expressions, and in some cases of selecting areas of a molecule that could not otherwise be distinguished. A list of the currently predefined sets is given below. In addition to the sets listed here, RasMol also treats element names (and their plurals) as predefined sets containing all atoms of that element type, i.e. the command select oxygen is equivalent to the command select elemno=8.
AT Acidic Acyclic Aliphatic Alpha Amino Aromatic Backbone Basic Bonded Buried CG Charged Cyclic Cystine Helix Hetero Hydrogen Hydrophobic Ions Large Ligand Medium Neutral Nucleic Polar Protein Purine Pyrimidine Selected Sheet Sidechain Small Solvent Surface Turn Water