^^DRY  Don't Repeat Yourself.

The DRY (Don't Repeat Yourself) Principle states:
Every piece of knowledge must have a single, unambiguous, authoritative representation within a system.

It's okay to have mechanical, textual duplication (the equivalent of caching values: a repeatable, automatic derivation of one source file from some meta-level description), as long as the authoritative source is well known.

 

Don't Repeat Yourself = OnceAndOnlyOnce

 

Links

Original: c2.com

Master e copie. Ri-produrre. Produrre originali e copie.