In general, one document (the transcription, T) is said to be a transcription of another document (the exemplar, E) if T was copied out from E with the intent, successfully achieved, of providing a faithful representation of a text as witnessed in E. Often the purpose is to make some representation which is easier to use than E is. For example, T may be easier for modern eyes to read, or easier to duplicate. Or T may be able to travel while E cannot.