User's Guide - Key Concepts
Built-in variables are automatically provided for you by AutoPlay Media Studio. They are used to represent common values that might differ between systems, like the location of the user's temp directory (%TempDir%) or the path to the user's Program Files folder (%ProgramFiles%). These variables serve as pre-defined constants that you can use in the paths and conditional expressions within your AutoPlay Media Studio project.
There are also built-in variables that provide valuable information about your AutoPlay application itself, such as the name of the previously viewed page at run time (%PageBackward%) and the page that you specified as the startup page for your AutoPlay application (%PageStart%). You can use these variables to make your AutoPlay application easier to navigate and otherwise behave the way you want it to.
Finally, there are built-in variables that you can use in action lists to get information about the last action that was performed (%LastActionID%), and in the case of an error, to get information about the type of error that occurred (%LastErrorNum%, %LastErrorMsg% and %LastErrorDetails%).
Next: Custom Variables