This command jumps to a PGC in the system space which can be one of the following:

First-Play PGC.
Title menu in the Video Manager.
Entry PGC in the Video Manager.
Root menu of a Video Title Set.
Subpicture menu of a Video Title Set.
Audio menu of a Video Title Set.
Angle menu of a Video Title Set.
Chapter menu of a Video Title Set.

CallSS can be present only in the Video Title Set Title (VTS) domain. The root menu and other VTS menus in the current VTS are often linked to from PGCs in the title domain with this command. A chapter (program PGN) may contain more than one cells. If a chapter has only one cell, after CallSS is executed, the virtual command RSM can be issued from the menu VTSM domain to resume playback from where it was left off (the current and only cell). If a chapter contains multiple cells, a cell number can be specified so that when RSM is executed, the specified cell is played back from its beginning.

Since the system space encloses only the menu space and the first-play domain, the title domain (Video Title Set VTS domain) is not part of the system space. CallSS links a PGC from the title domain to a PGC in system space to emphasize the restriction that the title domain is not in the system space. JumpSS links PGCs within the system space.

Jump to PGC in System Space
CallSS    First-Play PGC Title Menu Root Menu Subpicture Menu Audio Menu Angle Menu Chapter Menu   Resume cell PGC in Video Manager
DVD Command	Hex Encoding
CallSS Root Menu, Resume cell 1	30 08 00 00 01 83 00 00

This command can be combined with the Compare GPRM operations for conditional branching. When combining, this command is executed only if the result of the comparison is true.

1) Compare to another GPRM register and CallSS
2) Compare to another SPRM register and CallSS