There are three types of navigation commands. Each command takes 8 bytes of memory storage regardless of the amount of combining of commands.

Type-1 commands are GoTo, Link, and Jump. These commands can be combined with compare operations and are still treated as type-1 instructions, since there is none or only one operation performed depending on the compare result. These are Compare GoTo, Compare Link, and Compare Jump.

Type-2 commands are made from two instructions. One of the instruction changes the contents of a GPRM (see SetGPRM) or SPRM register (see SetSystem). The other instruction is a Link instruction or a compare operation.

Type-3 commands are made from the Compare, Set, and Link by SubInstruction commands, which perform three functions.

The following table summarizes different types of virtual commands typically deployed by commercial DVDs. The rightmost column (#) indicates the number of instructions (actions performed) for the corresponding command type.

Command	Type	Description	#
GoTo	1	Change the execution order of the navigation commands.	1
Link	1	Start the specified presentation within the domain (includes setting of the highlight button).	1
Jump	1	Start the specified presentation within another domain.	1
Compare GoTo	1	If the result of the compare is true, then GoTo.	2
Compare Link	1	If the result of the compare is true, then Link.	2
Compare Jump	1	If the result of the compare is true, then Jump.	2
SetSystem	2	Set navigation parameters (SPRMs and GPRMs).	1
Set GPRM	2	Compute GPRM value.	1
Compare SetSystem	2	If the result of the compare is true, then SetSystem.	2
Compare Set	2	If the result of the compare is true, then Set.	2
SetSystem Link	2	SetSystem and then Link.	2
Set Link	2	Set and then Link.	2
Set Compare Link by SubInstructions	3	Set and if the result of the compare is true, then Link by SubInstructions.	3
Compare & Set - SubInstructions	3	If the result of the compare is true, then Set and Link by SubInstructions.	3
Compare-Set & SubInstructions	3	If the result of the compare is true, then Set, and (ignoring compare) Link by SubInstructions.	3
Command	Type	Description	#