* @param offset the offset into base
     * @param len the length of the range
     * @return an array of vids that share all the chars of the range
     */
    public String[] getVersionsOfRange( short base, int offset, int len )
    {
        try
        {
            BitSet bs = getVersionSetOfRange( base, offset, len );
            if ( bs != null )
            {
                String[] vids = new String[bs.cardinality()];
                for ( int j=0,i=bs.nextSetBit(1);i>=0;i=bs.nextSetBit(i+1) ) 
                {
                    vids[j++] = getGroupPath((short)i)+"/"+getVersionShortName(i);
                }
                return vids;
            }
            else
                return new String[0];
        }
        catch ( Exception e )
        {
            return new String[0];
        }
    }