The symbol type. A The symbol's value is absolute, and will not be changed by further linking. The symbol is common.
Common symbols are uninitialized data.
When linking, multiple common symbols may appear with the same name. If the symbol is defined anywhere, the common symbols are treated as undefined references. D The symbol is in the initialized data section. G The symbol is in an initialized data section for small objects. Some object file formats permit more efficient access to small data objects, such as a global int variable as opposed to a large global array.