-c    Create/Edit file comments for all files
  -ac   Create/Edit file comments for all files during update
  -C    Add comments for new files only

  Each individual file contained within a .ZIP file may have a comment
  attached to it.  Comments are useful for identifying files, especially if
  you need to go back months later to look at a file, or if you are sending
  the file to someone else.  Each comment may be up to 59 characters long,
  including spaces and punctuation.

  The -c (lower case) option is used when you want to add or edit file
  comments for all files within an existing .ZIP file.

  The -ac option may be used during the .ZIP file creation process, or
  during an update/freshen process.  This will add comments for new files as
  well as allowing you to edit/add comments for files that were already in
  the .ZIP file.

     pkzip test.zip -ac license.doc

  When each file is added to the .ZIP file you will be prompted for a
  comment.  Type a comment of up to 59 characters, and press [ENTER].  If
  you are updating an existing .ZIP file and there are files which already
  have comments, the comment will be displayed on the prompt line for you to
  edit.  You may make changes or simply press [ENTER] to leave it unchanged.

  The -C (upper case) option is used when you want to add a file comment to
  new files that are being added to an existing .ZIP file.  Files which are
  not being added, or files which already existed in the .ZIP file will not
  be prompted for comments.

     pkzip test.zip -C *.doc

  In this situation, you would be adding additional files to the file called
  test.zip.  Since the file license.doc was added to it in the previous
  example, you would not be prompted for a comment for this file.