First thing: 0xC
= C (hex)
= 12 (dec)
= 1100 (bin)
. Four bits. Each and every character in the string C000000000000001
denotes four bits, 64 bits total. Binary representation of the string is 11…01
where …
replaces 60 zeros.
The meaning of these bits (from Wikipedia):
0 Platform required (required by the computer to function properly, OEM partition for example, disk partitioning utilities must preserve the partition as is)
1 EFI firmware should ignore the content of the partition and not try to read from it
2 Legacy BIOS bootable (equivalent to active flag (typically bit 7 set) at offset +0h in partition entries of the MBR partition table)
3–47 Reserved for future use
48–63 Defined and used by the individual partition type
It's not immediately obvious which bit in your 11…01
sequence is 0th, which is 63rd. Are the numbers offsets in the bit sequence? or is the 0th bit the least significant (rightmost) bit in the resulting binary number? Well, in my tests with (Linux) gdisk
I toggled the 0th bit and the attributes toggled between 00…00
and 00…01
, so I would say 0th is the least significant bit in the resulting binary number.
Which means your interpretation of the (hexadecimal) digit 1
is right (although not complete, the digit includes information about bits 1, 2 and 3 as well, these bits are unset).
gdisk
displays its own interpretation as:
0: system partition
1: hide from EFI
2: legacy BIOS bootable
60: read-only
62: hidden
63: do not automount
This agrees with Wikipedia when it comes to bits 0-2, and with this other answer and the link therein for 60, 62 and 63. I would treat those latter bits with a grain of salt, since Wikipedia states that
48–63 Defined and used by the individual partition type
and you didn't tell us what the partition type is, so we cannot really investigate further. On the other hand I wouldn't be surprised if Windows used its rules to all partition types. The fact your setup "works across multiple computers with no data corruption yet" suggests that at least for this particular partition Windows uses its rules regarding bits 62 and 63.
To summarize, the attributes in question mean:
- disk partitioning utilities must preserve the partition as is,
- hidden,
- do not automount.
This setup should work for you and not possess any threat to data stability.