| Contant Name | Description |
| _JEXEC | Anti direct access constant. Is defined in Joomla entry point and should be checked at the beginning of every Joomla Extension PHP file |
| JPATH_BASE | The SERVER SIDE path (not the http://.. Address!!) of the entry point in Joomla! It differs if you are on frontend or backend!! |
| DS | The OS Specific Directory sepparator (/ for linux, \ for windows) |
| JPATH_ROOT | The SERVER SIDE path of the root directory of the file system in native format |
| JPATH_SITE | File path to the root of the website |
| JPATH_CONFIGURATION | File path to where the configuration file lies |
| JPATH_ADMINISTRATOR | File Path to the administrator folder |
| JPATH_XMLRPC | File Path to the RPC Joomla script |
| JPATH_LIBRARIES | File Path to the Libraries |
| JPATH_PLUGINS | File Path to the Plugins folder (Mambots) |
| JPATH_INSTALLATION | File Path to the installation folder |
| JPATH_THEMES | File Path to the Templates folder |
| JPATH_COMPONENT | File Path to the ACTIVE component (differs if it’s admin backend or frontend). It’t the path to the active component entry point |
| JPATH_COMPONENT_SITE | File Path to the ACTIVE component frontend |
| JPATH_COMPONENT_ADMINISTRATOR | File Path to the ACTIVE component admin backend |
| JREQUEST_NOTRIM | Contant for JRequest calls |
| JREQUEST_ALLOWRAW | Contant for JRequest calls |
| JREQUEST_ALLOWHTML | Contant for JRequest calls |
| JVERSION | Current Joomla Version number (ex 1.5.9) |
| JDEBUG | Is 1 if debug mode is on |
| JERROR_ILLEGAL_OPTIONS | Error code |
| JERROR_CALLBACK_NOT_CALLABLE | Error code |
| JERROR_ILLEGAL_MODE | Error code |
| JPATH_ISWIN | True if the Server OS is windows |
| JPATH_ISMAC | True if the Server OS is Mac |
| _JLEGACY | Defined if Legacy Mode on |
| _ISO | Legacy Constant containing the Website character set |
| _VALID_MOS | Legacy Contant |
| _MOS_MAMBO_INCLUDED | Legacy Contant |
| _DATE_FORMAT_LC | Legacy Contant |
| _DATE_FORMAT_LC2 | Legacy Contant |
| _MOS_NOTRIM | Legacy Contant for JRequest calls |
| _MOS_ALLOWHTML | Legacy Contant for JRequest calls |
| _MOS_ALLOWRAW | Legacy Contant for JRequest calls |
