See Section 5 for information relating to the Disk File Manager.
K1 FMSZPG* [0043,7] -- FMS reserved space
FMSZPG is the reserved space in the database for the variables shown below; the names associated with K2 through K5 are not in the system equate file.
K2 ZBUFP* [0043,2] -- Buffer pointer K3 ZDRVA* [0045,2] -- Drive pointer K4 ZSBA* [0047,2] -- Sector buffer pointer K5 ERRNO* [0049,1] -- Error number