Offset Size Contents
+0       2  wVersion     ignored; not used
+2       4  pfrNext      addr of previous handler's SwStartupInfoRec
+6       4  res1         ignored; not used
+0aH      4  res2         ignored; not used
+0eH      4  pfarInst     address of list of SwInstanceItemRec structures.
18               size of an SwStartupInfoRec structure

pfrNext  this is the address of the next SwStartupInfoRec in the chain;
it is stored by programs which intercept INT 2fH 4b05H
(identify instance data).

pfarInst  the FAR address of a series of SwInstanceItemRec structures
that identify memory regions which must be kept unique for
each session.  The structures are sequential in memory, and
the list ends when the first field if the SwInstanceItemRec is

This structure is used in INT 2fH 4b05H (identify instance data).  It is
part of the system that allows programs to be reentrant across multiple
tasks by reserving memory areas for buffers and variables.  The task
switcher will save and restore the correct data for each task.

Programs that need to maintain instance data typically have the switcher
save and restore their stack, along with a specially-defined portion of
their data segment (including some or all program variables).

INT 2fH 4bxxH (switcher functions)
- -