; ==========================================================================
function filename_3c,hem,year,version,revision,type,ext,tag_preliminary
    ; ==========================================================================
    ; This function constructs the various CIPS Level 3C file names given the
    ; following input:
    ;
    ;          hem    hemisphere ('north' or 'south')                  string
    ;         year    year (e.g. '2009')                               string
    ;      version    CIPS data version # (e.g., '05.20')              string
    ;     revision    CIPS data revision # (e.g., '04')                string
    ;         type    3c file type (e.g., 'cld')                       string
    ;          ext    3c file extension ('nc' or 'sav')                string
    ;
    ; Note: As of November 7, 2019, now handles an empty string passed for
    ;       the 'type' parameter, to support the ; ver05.20 rev05
    ;       single-file format (P. E. Meade)
    ; -------------------------------------------------------------------------

    y1=strmid(strtrim(year,2),2,2)
    y2=strmid(strtrim(year+1,2),2,2)
    
    if(hem eq 'south') then season=hem+'_'+y1+y2 else season=hem+'_'+y1
    
    root='cips_3c_'+season+'_v'+version+'_r'+revision
    if (type ne '') then root=root+'_'
    if (tag_preliminary) then $
       file=root+type+'_prelim.preliminary.'+ext $
    else $
       file=root+type+'.'+ext
    
    return,file
end