2.4.6 Attributes and Qualifiers

The compiler keyword __attribute__ allows you to specify special attributes of variables, structure fields or functions. This keyword is followed by an attribute specification inside double parentheses, as in:

int last_mode __attribute__ ((persistent));

In other compilers, qualifiers are used to create qualified types:

persistent int last_mode;

The MPLAB XC-DSC C/C++ Compiler for dsPIC33C/E/F and dsPIC30 DSC does have some non-standard qualifiers described in the 9.9 Compiler-Specific Type Qualifiers - C section.

Generally speaking, qualifiers indicate how an object should be accessed, whereas attributes indicate where objects are to be located. Attributes also have many other purposes.