When provided with CD-ROM reader hardware with multisession capability, Joliet receiving systems shall receive media recorded using the multisession recording technique.
The details of this technique are provided below
Each sector on the media is assigned a unique Logical Sector Address.
Logical Sector Addresses zero and above increase linearly across the surface of the disc, regardless of session boundaries.
Logical Sector Address zero references the sector with Minute:Second:Frame address 00:02:00 in the first session. All other Logical Sector Addresses are relative to Minute:Second:Frame address 00:02:00 in the first session.
The conversion between Logical Sector Addresses and Minute:Second:Frame addresses is Logical Sector Address = (((Minute*60)+Seconds)*75) - 150.
Simply put, the Logical Sector Address on a multisession disc describes a flat address space.
The data area for a volume may span multiple sessions.
For example, if a disc is recorded with 3 sessions, the directory hierarchy described by a volume descriptor in session 3 may reference logical sectors recorded in session 1, 2, or 3.
The Volume Recognition Sequence shall begin at the 16th logical sector of the first track of the last session on the disc.
This volume recognition sequence supersedes all other volume recognition sequences on the disc. The interpretation of the Volume Recognition Sequence is otherwise unchanged.
For example, consider a disc that contains 3 sessions, where session 1 starts at 00:00:00, session 2 starts at 10:00:00, and session 3 starts at 20:00:00. The Volume Recognition Sequence for this disc would start at Minute:Second:Frame address 20:00:16.
This technique is compatible with the CD-Bridge multisession technique.
The data area for a Joliet volume on a CD-ROM shall be comprised of either Mode 1 or Mode 2 Form 1 sectors. CD-ROM media utilizing the multisession recording techniques outlined above may not contain any Mode 1 sectors anywhere on the media. Mode 1 sectors are allowed only on single-session media.
Mode 2 Form 2 sectors and CD-Digital Audio tracks may be recorded on the same media as a Joliet volume. In this case, the CD-XA extensions to Joliet may be utilized to identify Mode 2 Form 2 extents and CD-Digital Audio extents.
CD-Digital Audio tracks may not be recorded in sessions 2 and higher. If any CD-Digital Audio tracks are recorded, all the CD-Digital Audio tracks shall be recorded in the first session.
CD-ROM discs utilizing the Joliet extensions to ISO 9660 and which also identify mode 2 form 2 extents or CD-Digital Audio extents shall be marked with a CD-ROM XA Label as specified in "System Description CD-XA" section 2.1.
The CD-ROM XA Label shall be located at offset 1024 (byte position 1025) in the Joliet Supplementary Volume Descriptor. The identifying signature 'CD-XA001' shall be recorded starting at offset 1024 in the Joliet Supplementary Volume Descriptor. This identifying signature is equivalent to the hex bytes (43)(44)(2D)(58)(41)(30)(30)(31).
Mode 2 form 2 extents shall be identified using recording rules outlined in "System Description CD-XA", section 2.7. In this case, bit 12 of the Attributes field of the "XA System Use Information" shall be set to one to identify that the file contains mode 2 form 2 sectors. See below for additional information regarding Data Length.
CD-Digital Audio extents shall be identified using recording rules outlined in "System Description CD-XA", section 2.7. In this case, bit 14 of the Attributes field of the "XA System Use Information" shall be set to one to identify that the file is comprised of an extent of CD-Digital Audio. See below for additional information regarding Data Length.
If a file is marked such that either bit 12 is set to one or bit 14 is set to one in the Attributes field of the "XA System Use Information", then the Data Length field of the Directory Record shall be set to 2048 times the number of sectors contained in the extent. See ISO 9660:1988 section 9.1.4.
The Joliet Extensions to ISO 9660 are designed to coexist with other extensions such as the "System Use Sharing Protocol" and "RockRidge Interchange Protocol". However, these protocols are not an integral part of the Joliet specification.
The method used to integrate these other protocols into Joliet is not defined here.