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$_DOCUMENT_ROOT VARIABLE
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  DESCRIPTION
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    The $_DOCUMENT_ROOT variable stores the physical path to the PTM developer's
    root web accessible directory and should be manually set at the time of PTM
    installation. It can be the full physical path, or the relative path from
    the PPA (PTM Parser Application) [ptm.cgi] to the document root directory.
    In the rare instance that you are on a 100% dedicated server and the default
    DocumentRoot directory assigned in Apache's httpd.conf file is your document
    root, this variable does not need to be set, as the PPA will default to
    Apache's defined DocumentRoot. In all other circumstances it must be set to
    your personal root web accessible directory, as it is used to locate
    requested script files and is used in creation of the $_PATH variable, which
    stores the directory to which the PPA will set its working directory. Even
    if you are only going to be using PTM scripts in a subdirectory of your
    site, it is necessary to set this variable to the root web accessable
    directory, because the relative paths it creates later on are based with the
    belief that they are relative to the lowest web accessible directory in the
    file tree.

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  SEE ALSO
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    VARIABLES

      $_BASE, $_PATH, $_SCRIPT, %_SERVER, $_URL