The ADV_OBJ directory must be present at the top level of all HD DVD discs containing Advanced Content. All Playlist files shall reside directly under this directory. Any files of Advanced Navigation, Advanced Element, and Secondary Video Set can reside directly under this directory.

Playlist

Playlist files have an extension of "XPL" (or "xpl").

A Playlist file may be necessary to be read from a disc as described in Startup Sequence of Advanced Content. In this case the file may be of two types, those with filenames "VPLSTxxx.XPL" for a player which connects with a dsiplay device, or the filenames "APLSTxxx.XPL" for a player which does not connect with a display device. xxx is a number between "000" and "999".

In this case, the Playlist file which has the maximum number shall be read initially in the startup sequence. The file must be found directly under the ADV_OBJ directory, not within its sub-directories.

Otherwise a playlist file may be found in sub-directories under the ADV_OBJ directory, and the file name rules are relaxed.

Configuration File

This file shall reside directly under the ADV_OBJ directory, and must have the filename "DISCID.DAT", even if functions for a network connection or Persistent Storage are not required in a disc.

Certificate

This file may reside directly under the ADV_OBJ directory, and has an extension of "CER" or "cer".

Directories for Advanced Content

Directories for Advanced Content may exist only under the ADV_OBJ directory. Any files of Advanced Navigation, Advanced Element and Secondary Video Set can reside in this directory. The number of sub-directories shall be less than 512, and directory depth shall be less than or equal to 8. (Excluding the ADV_OBJ directory itself). Directory names must conform to the character set described for files, below.

Files for Advanced Content

The total number of files under the ADV_OBJ directory shall be limited to 512 x 2047, and the total number of files in each directory shall be less than 2048. The character code set is limited to a subset of ISO 8859-1, that is: "A to Z a to z 0 to 9 space !$%&'(),-.;=@_" (20h, 21h, 24h to 29h, 2Bh to 2Eh, 30h to 39h, 3Bh, 3Dh, 40h to 5Ah, 5Fh, 61h to 7Ah). The length of the filename must not exceed 255 characters.

File names must be chosen so that they are unique in both case-sensitive and case-insensitive systems. All instances of the same name shall be recorded as if in a case-sensitive system, and the player shall preserve the upper and lower case of filenames.

It is acceptable for an HD DVD-Video disc to contain one or more zero byte files.

See File Extension and MIME Type for a list of the supported file types.