The basic transformations can be divided into four categories: project, select, control, and output. The control and output transformations aren't quite transformations like project and select, but that is what we'll call them for consistency.
Throughout this section of the document, transformations are denoted as if they were functions, but in reality they are Perl arrays. This presentation allows the concepts to be discussed, without the complication of Perl syntax. See TransInt, for information on how to manipulate them.