The Lisp reader takes characters from a stream, interprets them as a printed representation of an object, constructs that object, and returns it.
The syntax described by this chapter is called the standard syntax. Operations are provided by Common Lisp so that various aspects of the syntax information represented by a readtable can be modified under program control; see Section 23 (Reader). Except as explicitly stated otherwise, the syntax used throughout this document is standard syntax.
2.1.2 Variables that affect the Lisp Reader