I don't know, WordLine maybe??
WL NAND has subpages.. ie: TLC NAND..
WL Mode
Page 123 - Lower - Prefix 01h
Page 123 - Middle - Prefix 02h
Page 123 - Upper - Prefix 03h
SLC Mode
Page 123 - Prefix A2h
SLC Mode is pretty cool, you lose 2/3rds capacity but gain reliability and speed by merging the subpages into one.