I could find this patch set with the comment:
/* Pre-uniarch versions of binutils stored machine types in the
* e_flags field, with values up to 471 decimal. Now we store the
* machine type in the e_mach field, and use e_flags to identify the
* characteristics of the code.
*
* Use the following flag to indicate that this object file uses the
* uniarch flag layout. */
#define EF_MSP430_UNIARCH 0x10000000
#define EF_MSP430_ARCH_430 0x00000000
#define EF_MSP430_ARCH_430X 0x00000001
#define EF_MSP430_ARCH 0x000000FF
#if 0
/* These are symbol-associated, not archive-associated, attributes.
* Not sure what to do with them. */
#define EF_MSP430_CPU_430 0x00000000
#define EF_MSP430_CPU_430X 0x00000200
#define EF_MSP430_CPU_430XV2 0x00000300
#define EF_MSP430_CPU 0x00000300
#define EF_MSP430_MPY_NONE 0x00000000
#define EF_MSP430_MPY_16 0x00001000
#define EF_MSP430_MPY_16_SE (0x00008000 + EF_MSP430_MPY_16)
#define EF_MSP430_MPY_32 0x00002000
#define EF_MSP430_MPY_32_DW (0x00008000 + EF_MSP430_MPY_32)
#define EF_MSP430_MPY_CLASS 0x00003000
#define EF_MSP430_MPY 0x0000F000
#define EF_MSP430_CODE_NEAR 0x00010000
#define EF_MSP430_CODE_FAR 0x00020000
#define EF_MSP430_CODE_MIXED 0x00030000
#define EF_MSP430_CODE 0x00030000
#define EF_MSP430_DATA_NEAR 0x00040000
#define EF_MSP430_DATA_FAR 0x00080000
#define EF_MSP430_DATA_MIXED 0x000c0000
#define EF_MSP430_DATA 0x000c0000
#define EF_MSP430_A20 0x000F0000
#endif
And apparrently an older version:
/* Processor specific flags for the ELF header e_flags field. */
#define EF_MSP430_MACH 0xff
#define E_MSP430_MACH_MSP430x11 11
#define E_MSP430_MACH_MSP430x11x1 110
#define E_MSP430_MACH_MSP430x12 12
#define E_MSP430_MACH_MSP430x13 13
#define E_MSP430_MACH_MSP430x14 14
#define E_MSP430_MACH_MSP430x15 15
#define E_MSP430_MACH_MSP430x16 16
#define E_MSP430_MACH_MSP430x31 31
#define E_MSP430_MACH_MSP430x32 32
#define E_MSP430_MACH_MSP430x33 33
#define E_MSP430_MACH_MSP430x41 41
#define E_MSP430_MACH_MSP430x42 42
#define E_MSP430_MACH_MSP430x43 43
#define E_MSP430_MACH_MSP430x44 44