Nested Multi-variable _Generic Macro function in C11

#ifndef BITIOBYTEBITORDERS
#define BITIOBYTEBITORDERS

#ifndef BitIOLittleEndian
#define BitIOLittleEndian ULLONG_MAX
#endif  /* BitIOLittleEndian */

#ifndef BitIOBigEndian
#define BitIOBigEndian    LDBL_MAX
#endif  /* BitIOBigEndian */

#ifndef BitIOLSBit
#define BitIOLSBit        ULLONG_MAX
#endif  /* BitIOLSBit */

#ifndef BitIOMSBit
#define BitIOMSBit        LDBL_MAX
#endif  /* BitIOMSBit */
#endif  /* BITIOBYTEBITORDERS */

typedef unsigned long long   BitIOLittleEndian_t;
typedef long double             BitIOBigEndian_t;
typedef unsigned long long          BitIOLSBit_t;
typedef long double                 BitIOMSBit_t;

#define ReadBits(ByteOrder,BitOrder,BitB,Bits2Read)\
_Generic((ByteOrder),\
BitIOLittleEndian_t:_Generic((BitOrder),BitIOLSBit_t:ReadBitsFromLELSBToLELSB,BitIOMSBit_t:ReadBitsFromLEMSBToLELSB),\
BitIOBigEndian_t:_Generic((BitOrder),BitIOLSBit_t:ReadBitsFromBELSBToLELSB,BitIOMSBit_t:ReadBitsFromBEMSBToLELSB))\(BitB,Bits2Read)