NAME:
       ONLINE_HELP_PDF_INDEX

 PURPOSE:
       Widget utility that allows the user to select an entry from
       the IDL documentation master index, then display the selected
       page in the Adobe Acrobat viewer. This is meant to be called
       by ONLINE_HELP on UNIX systems when the supplied topic name
       does not exist.

       This utility only works on platforms that support the IDL-Acrobat
       plug-in: currently all Unix platforms except AIX and OS X.

       This utility relies on the presence of a file containing a
       text-only copy of the IDL Master Index document. The file is
       located in the help subdirectory of the IDL distribution, and
       is called 'mindex.txt'.

 CATEGORY:
       Help, documentation.

 CALLING SEQUENCE:
       ONLINE_HELP_PDF_INDEX [, TopicString] [, /EXACT]

 INPUTS:
     TopicString: A scalar string containing the item about which
     help is desired.

 KEYWORD PARAMETERS:
     EXACT: Set this keyword to specify that TopicString is
     an exact match of a valid named destination (as returned
     by the ONLINE_HELP_PDF_ND2FILE function).

     Note: this keyword is not documented and its behavior
     may change in future releases. It is inteded for use by
     the ONLINE_HELP procedure and ? command, which know how
     to determine whether a string is in fact a valid desintation.

 OUTPUTS:
       Display the widget interface. If the EXACT keyword is set,
       (implying that TopicString exactly matches a naed destination
       in one of the IDL docset PDF files), check the saved
       preferences to determine whether the widget interface should
       be displayed.

 CALLS: ***
	ADDBOOKMARK, DELETEBOOKMARK, DONE_EV, EDITBOOKMARK, FILEPATH, GETBOOKMARKS, GO_EV
	HELP_EV, HIGHLIGHTPAGENUM, LIST_SEARCH_EV, LIST_SELECT_EV, NOTHING_EV
	ONLINE_HELP_PDF_INDEX_EVENT, PATH_SEP, PICKBOOK, SELECTPAGENUM, SHOWHELP
	SHOWPREF_EV, STRSPLIT, TAB_CHANGE_EV, WRITEBOOKMARKS, XMANAGER, XREGISTERED
 COMMON BLOCKS:
       ONLINE_HELP_PDF_INDEX - This block is private to this module,
       and not to be used by other routines.

 MODIFICATION HISTORY:
       29 April 2004, DD

 NAME:
       ONLINE_HELP_PDF_ND2FILE

 PURPOSE:
       Given a pdf named destination, this function returns the name
       of the IDL documentation pdf file from !HELP_PATH in which the
       named destination is expected to be found.

       This function is called by the IDL builtin ONLINE_HELP procedure
       when pdf files are being used, and the IDL user specifies a
       search topic without also giving the name of the pdf file. It uses
       RSI supplied .pdf_nd files to determine the file to use, returning
       the name of the file if found, and a NULL string otherwise.

        -------------------------------------------------------------
       | THIS ROUTINE IS NOT INTENDED FOR GENERAL USE. IT MAY CHANGE |
       | OR EVEN BE REMOVED FROM FUTURE IDL RELEASES WITHOUT NOTICE. |
        -------------------------------------------------------------

       The public interface to the functionality contained in this routine
       is via the "?" command, or the ONLINE_HELP procedure.

 CATEGORY:
       Help, documentation.

 CALLING SEQUENCE:
       ONLINE_HELP_PDF_ND2FILE, NamedDestination

 INPUTS:
     NamedDestination: A scalar string containing the item about which
     help is desired.

 OUTPUTS:
       Returns a string giving the name of the pdf file to use, or
       NULL if no file is found,

 CALLS: ***
	PATH_SEP, STRSPLIT, UNIQ
 COMMON BLOCKS:
       ONLINE_HELP_PDF_ND2FILE - This block is private to this module, and
               not to be used by other routines.

 MODIFICATION HISTORY:
       13 March 2003, AB

 NAME:
	OPLOTERR

 PURPOSE:
	Overplot data points with accompanying error bars.

 CATEGORY:
	Plotting, 2-dimensional.

 CALLING SEQUENCE:
	OPLOTERR, [ X ,]  Y , Err  [, Psym ]

 INPUTS:
	Y:	The array of Y values.

	Err:	The array of error bar values.

 OPTIONAL INPUT PARAMETERS:
	X:	An optional array of X values.  The procedure checks whether 
		or not the third parameter passed is a vector to decide if X 
		was passed.
		
		If X is not passed, then INDGEN(N_ELEMENTS(Y)) is assumed for 
               the X values.

	PSYM:	The plotting symbol to use (default = +7).

 COMMON BLOCKS:
	None.

 SIDE EFFECTS:
	None.

 RESTRICTIONS:
	Arrays cannot be of type string.  There must be enough points to
	plot.

 PROCEDURE:
	A plot of X versus Y with error bars drawn from Y - ERR to Y + ERR
	is written to the output device over any plot already there.

 MODIFICATION HISTORY:
	William Thompson	Applied Research Corporation
	July, 1986		8201 Corporate Drive
				Landover, MD  20785
       kdb, March, 1997  - Fixed a problem if 1 element arrays where used.