Session issues.
  Writing to a CD is called a session and entails writing some additional
    overhead before recording data and writing additional overhead after
    data is written.

  Original CD-R allowed a single session DAO (disc at once) - one 
    uninterrupted write. Audio CDs are always single session.

  Newer burners allow for TAO (track at once). 

  The concept of a track comes from the musical industry and allowed them to 
    break the CD up into up to 99 addressable locations for the start of a song.

  A track is at least 300 blocks (sectors).

  A disk can have up to 99 writes.
   
  TAO allows the burning laser to be turned off and at a later time 
    re-positioned correctly to continue burning. This introduces a small gap 
    between recorded "tracks" of data. 

  To use TAO, the disk is opened in a session and is not usable until all
    tracks are burned and the session is closed.  VTOC is updated 
    (written/rewritten) once the session is closed. 

  The gaps may cause popping and crackling between songs and some music
    CD readers may not handle this type of disk.

  A session (DAO, TAO recording) on a CD requires a lead long in and lead 
    out to mark it.  

  Newer protocols allow for multi-session TAO (track at once) - more than one 
    writing but minimum of 1 track length. But only for mode 1 and mode 2 XA

  A music CD can be made with TAO recording, but only the 1st session is
    accessible as a music CD.

  Each session must be closed before another is started. For CD-R/CD-ROM,
    disc cannot be read until session closed. CD-RW has more flexibility.

  Each track adds a 2-block run-out. The next track also adds 1-block link and
  a 4-block run-in. 

  Additionally each session requires additional lead in and lead out blocks 
    and causes the VTOC to be re-written.
 
 (Make sure your burning software has completed everything and is closed
    before removing CD from drive.)

  Newest protocols allow for packet writing.