function doc_cats, count, yohkoh=yohkoh, general=general, $
	toplev=toplev, class=class,  descript=descript
;
;+
;   Name: doc_cats
;
;   Purpose: string array of currently registered documentation categories
;
;   Output Parameters:
;      function returns string array of requested categories
;      count - number of elements returned
;
;   Keyword Parameters:
;      yohkoh, general, toplev, class - input switches for selection
;      descript - output, desription of return values 
;    
;   Calling Sequence: 
;	categors=doc_cats([/toplev] [descript=descript, /class] [/yohkoh] [general])
;
;   Category: swmaint, documentaion, help
;
;   History: slf, 25-Jul-92
;            slf, 10-Dec-92 added count parameter, 
;			    changed decript to keyword
;-
;
; general purpose categories
gen=   [							$
      'mathmatics','numerical','input/output', 'file',		$
      'graphics','plotting','image display','image processing', $
      'help','swmaint','programming','documentation',		$
      'array','string','structure',   				$
      'registration','response','sensitivity', 			$
      'widgets','xwindows',					$
      'magnetic tape','operating system','unix only','vms only',$
      'idl fix'							]
;
; yohkoh specific categories
yoh  =[							        $
      'dbase','reformatter','ref_access', 'orbit', 		$
      'time','week','fileid',					$
      'spectral analysis','time series',			$
      'engineering','telemetry'					]

; top level categories
top   =[							$
        'gen','sxt','bcs','wbs','hxa','site'			]

; routine classes
cls   =[							$
       'class1','class2','class3','class4','class5'		]
   
;class descriptions 
cdesc=[								$
	'Top Level User Program',				$
	'High Level Interactive Routine',			$
	'General Purpose Utilities',				$
	'Programmer / System Level Routines',			$
	'Limited & Single use routines'				]

case 1 of 
   keyword_set(yohkoh) and  1-keyword_set(general): 	$
      categories=[yoh]
   keyword_set(general) and 1-keyword_set(yohkoh):  	$
      categories=[gen]
   keyword_set(toplev):					$
      categories=[top]
   keyword_set(class):begin
      categories=[cls]
      descript=cdesc
   endcase
   else:						$
      categories=[gen,yoh]
endcase
;
count=n_elements(categories)
return,categories
end