What does the "aw" flag in the section attribute mean?

Question

In the following line of code (which declares a global variable),

unsigned int __attribute__((section(".myVarSection,\"aw\",@nobits#"))) myVar; 

what does the "aw" flag mean?

My understanding is that the nobits flag will prevent the variable from being initialised to zero, but I am struggling to find info about the "aw" flag.

Also, what meaning do the @ and # have around the nobits flag?