# valid names

Valid names for symbols may be constructed using letters, digits, and the apostrophe, and should not begin with a digit.
 i1 : x o1 = x o1 : Symbol i2 : q0r55 o2 = q0r55 o2 : Symbol i3 : f' o3 = f' o3 : Symbol
Some symbols have preassigned meanings and values. For example, symbols consisting of the letter o followed by a number are used to store output values.
 i4 : o2 o4 = q0r55 o4 : Symbol
Other symbols refer to functions built into Macaulay2 that provide much of its functionality, as we will learn.

The class of all symbols is Symbol.