The Daylight system represents a molecule as a graph in which the nodes are atoms and the edges are bonds. Each atom has a several properties, including its atomic number, atomic weight, charge, and the number of attached hydrogens. If the atom is a chiral center, it can also have chiral specifications. There is some flexibility in this valence model. Isotopic information such as chirality and atomic mass can be unspecified, partially specified, or completely specified.
Derived properties are properties that can be computed from the graph.
The following sections describe the derived properties that are of interest in the Daylight system. When a molecule's atoms and bonds are specified, it may be that there are cycles in the graph. Atoms that are connected via ring bonds are ring atoms . The algorithms used for these tasks are beyond the scope of this document. However, we will point out that of the two tasks above, the first is relatively trivial and the second is surprisingly complex.