Reactions in Databases:

There is no differentiation between reaction and molecule databases.

Reactions are stored in databases as TDTs. The reaction SMILES forms the root of the datatree, as follows:

"Unique" reactions:

• No agents or stereo.
  
• Atom maps suppressed.

"Absolute" reaction:

• All components and stereo.
• Atom map values.
  
• Used either as root of subtrees or as data (preferred).

The result of these normalizations is that reactions are stored together on the same TDT page if they contain the same unique reactant and product molecules.

A concern is inclusion of non-key molecules. In the following case, these two esterifications will be stored on different TDT pages in the database:

$SMI<"CC(=O)O.OCC>>CC(=O)OCC">|
$SMI<"CC(=O)O.OCC>>CC(=O)OCC.O">|

The solution has two parts: first, develop and enforce conventions for registration. Second, lookup by both reactant and product in Thor.