Block Tool

Function:  Plots the number of counts verses space-craft phase, pitch
	   angle, and energy for each detector.  It is used as a low-
	   level diagnostic tool.

Usage:     The idea is to flip through the data block-by-block.  The
           program is given an initial time for the block to be loaded,
	   and then it can be instructed to move to next or previous
           blocks.  

	   Load the closest block to 10:00:00 on 07/29/96, showing
	   electron counts:
	   IDL> block_tool, '960729', '10:00:00', /ele

	   Load the next block:
	   IDL> block_tool, /next

	   Load the previous block (back to the original block):
	   IDL> block_tool, /prev

	   Show the same block, but with ion counts:
	   IDL> block_tool, /ions
	   
	   Now produce a .gif file:
	   IDL> block_tool, /ions, /gif


Notes:     The program uses an eight-block buffer for efficient data-
	   loading.  If a new time is specified, or the user has stepped
	   out of the range of blocks in the buffer, there will be a 
	   short delay while more data is loaded.

	   /electrons (/ele) is the default if /ions is not specified.

           block_tool has the following arguments:
	     /next            or
	     /prev            or
             <date>, <time>.
	   All other keywords are passed on to the plotting routine,
	   which accepts the keywords:
	     /electrons
             /ions
             /gif
	   If no plotting-routine keywords are specified, then the
	   keywords from the previous invocation are used.  Therefore,
           in the initial call above, the plotting-routine keywords
	   are set to "/ele", and in the subsequent /next and /prev
	   calls, the keyword "/ele" is passed to the plotting routine.
	   Note that in the last call, /ions must be specified along
	   with /gif, since /gif is a plotting-routine keyword, otherwise
	   the plotting routine will default to electrons.



