Editing Chemical database (section)

== Chemical structure representation ==

There are two principal techniques for representing chemical structures in digital databases

* As connection tables / [[adjacency matrix|adjacency matrices]] / lists with additional information on [[chemical bond|bond]] (edges) and atom attributes (nodes), such as:
*:[[MDL Molfile]], [[Protein Data Bank|PDB]], [[Chemical Markup Language|CML]]
* As a linear string notation based on [[Depth-first search|depth first]] or [[breadth first search|breadth first traversal]], such as:
*:[[Simplified molecular input line entry specification|SMILES]]/SMARTS, [[SYBYL Line Notation|SLN]], [[Wiswesser Line Notation|WLN]], [[International Chemical Identifier|InChI]]

These approaches have been refined to allow representation of [[stereochemistry|stereochemical]] differences and charges as well as special kinds of bonding such as those seen in [[organometallic|organo-metallic]] compounds.  The principal advantage of a computer representation is the possibility for increased storage and fast, flexible search.