C Language Reference for @ and :

I am looking at some C code and I cannot find any language reference as to
what the '@' symbol or token means...

For, example, from the header file I am trying to interpret....

/////////////////////////////////////////////////////////////////
static unsigned char P1 @ 0x90;
static unsigned char P2 @ 0xA0;
static unsigned char P3 @ 0xB0;
/////////////////////////////////////////////////////////////////



Also what does these colons mean... ( I understand this is creating a new
type and it is a "public by default" class for a bit watching type.)  But
what does the colon do?  Initialize defualts?

/////////////////////////////////////////////////////////////////
typedef struct
{
   unsigned B0:1;
   unsigned B1:1;
   unsigned B2:1;
   unsigned B3:1;
   unsigned B4:1;
   unsigned B5:1;
   unsigned B6:1;
   unsigned B7:1;
} SFR;
/////////////////////////////////////////////////////////////////


Thanks,

Nate