Hi you both ,
it's normally used as numeric-volume-name , so in linux too, there a fstab from OpenMandriva..
UID and GID be User-Identification number and Group Identification, so UID and GID in the Userland ..
slowly also in Win10 for more coming in direction linux and supporting the Linux variables too and mappng the name, becase with numbers be more possible for possibility's and like in the past up to now on the Web ip mapping to the human read able "Names" (webname.domain) from this is coming the whole, because with numbers be more possibility to decide, and later it's more possible to decide for mapping this number with the builddate/number of the Factoryname of the harddisk, with exactly this UUID and saving later for a recognition of this device with this volumes and partitions .. because on this it's also possible for make a device UUID and at this point it is coming the confusion "danger" because a couples peoples of programmers do not really know and use a couple of different UUID for it and then becomes a muddled up.
sda = harddisk0
sdb = harddisk1
sdc = harddisk2
sdd = harddisk3
sde = harddisk4
sda1= Harddisk0/partition0 /+unique UUID
sda2= Harddisk0/partition1 /+unique UUID
sda3= Harddisk0/partition2 /+unique UUID
sda4= Harddisk0/partition3 /+unique UUID
sda5= Harddisk0/partition-extended-0 /+unique UUID
sda6= Harddisk0/partition-extended-1 /+unique UUID
sdb1= Harddisk1/partition0 /+unique UUID
sdb2= Harddisk1/partition1 /+unique UUID
sdb3= Harddisk1/partition2 /+unique UUID
sdb4= Harddisk1/partition3 /+unique UUID
sdb5= Harddisk1/partition-extended-0 /+unique UUID
sdb6= Harddisk1/partition-extended-1 /+unique UUID
the UUID it is setting up by creating and formatting of the partitions (imho) and it is writing also in the partitions tables.
therewith it is possible for changing/moving the hardware on different ports and be ever found to use..
so can you use this partition on port sda or sdz and the partition with UUID it is ever found and
mounting in the right mount point and can mount on the right place, behind the boot of the bootloader
up to the fstab and booting the system with the right partitions to the right mount points .