A sign on the sheet of assertion or on any other area, made by a single action or series of acts of scribing and expressive, according to the conventions of this system [of existential graphs], of an intelligible state of things, shall be called a graph-replica. The general type of all possible graph-replicas which would be similar to a given graph-replica in every significant respect, shall be called a graph.
http://www.commens.org/dictionary/entry/quote-existential-graphs-6