https://en.wikipedia.org/wiki/Partition_table

MBR
1.variant
primary /dev/sdx1....4

2.variant
primary /dev/sdx1..3
extended /dev/sdx4
logical /dev/sdx5...132  (kokku 128)

GPT
primary /dev/sdx1...128

https://www.maketecheasier.com/differences-between-mbr-and-gpt/