Enumerations, lists or character name arrays

Each atom has a set of `extra' data values, other than it's position. The codes used as indices for these extra data values are:

• ATOMCHARGE
• ATOMMASS
• ATOMBETA
• ATOMOCCUP
• ATOMRAD
• ATOMEXTRA - the number of `extra' data items.

The BackboneType enumeration lists the different types of backbone bonds which may exist:

• NORMAL - used if nothing else special about the backbone bond can be determined.
• PROTEINBACK - used for protein backbone bonds.
• NUCLEICBACK - used for nucleic acid backbone bonds.

The ResidueType enumeration lists the different classes of residues which this atom may be a part of:

• NOTHING - not in a residue of any noted special group.
• PROTEIN - a standard protein residue, i.e. an amino acid.
• NUCLEIC - a standard nucleic acid resiude, i.e. A,T,G,C, or U.
• WATERS - a solvent residue, most likely water.