Identifiers can have integral, float, enum, struct, union, array, pointer, or function type. An identifier is a primary expression provided it has been declared as designating an object (in which case it is an l-value) or as a function (in which case it is a function designator). See L-Value and R-Value Expressions for a definition of l-value.
The pointer value represented by an array identifier is not a variable, so an array identifier cannot form the left-hand operand of an assignment operation and therefore is not a modifiable l-value.
An identifier declared as a function represents a pointer whose value is the address of the function. The pointer addresses a function returning a value of a specified type. Thus, function identifiers also cannot be l-values in assignment operations. For more information, see Identifiers in Chapter 1.