local($_)=@_;
  return ""  if (! $_);

  my($y,$m,$d,$h,$mn,$s,$i,$wofm,$dofw,$wk,$tmp,$z,$num,$err,$iso,$ampm)=();
  my($date,$z2,$delta,$from,$falsefrom,$to,$which,$midnight)=();

  # We only need to reinitialize if we have to determine what NOW is.
  Date_Init()  if (! $Curr{"InitDone"}  or  $Cnf{"UpdateCurrTZ"});

  my($L)=$Cnf{"Language"};
  my($type)=$Cnf{"DateFormat"};

  # Mode is set in DateCalc.  ParseDate only overrides it if the string
  # contains a mode.
  if      ($Lang{$L}{"Exact"}  &&
           s/$Lang{$L}{"Exact"}//) {
    $Curr{"Mode"}=0;
  } elsif ($Lang{$L}{"Approx"}  &&
           s/$Lang{$L}{"Approx"}//) {
    $Curr{"Mode"}=1;
  } elsif ($Lang{$L}{"Business"}  &&
           s/$Lang{$L}{"Business"}//) {
    $Curr{"Mode"}=2;
  } elsif (! exists $Curr{"Mode"}) {
    $Curr{"Mode"}=0;
  }

  # Unfortunately, some deltas can be parsed as dates.  An example is
  #    1 second  ==  1 2nd  ==  1 2
  # But, some dates can be parsed as deltas.  The most important being:
  #    1998010101:00:00
  #
  # We'll check to see if a "date" can be parsed as a delta.  If so, we'll
  # assume that it is a delta (since they are much simpler, it is much
  # less likely that we'll mistake a delta for a date than vice versa)
  # unless it is an ISO-8601 date.
  #
  # This is important because we are using DateCalc to test whether a
  # string is a date or a delta.  Dates are tested first, so we need to
  # be able to pass a delta into this routine and have it correctly NOT
  # interpreted as a date.
  #
  # We will insist that the string contain something other than digits and
  # colons so that the following will get correctly interpreted as a date
  # rather than a delta:
  #     12:30
  #     19980101

  $delta="";
  $delta=ParseDateDelta($_)  if (/[^:0-9]/);

  # Put parse in a simple loop for an easy exit.
 PARSE: {
    my(@tmp)=Date_Split($_);
    if (@tmp) {
      ($y,$m,$d,$h,$mn,$s)=@tmp;
      last PARSE;
    }

    # Fundamental regular expressions

    my($month)=$Lang{$L}{"Month"};          # (jan|january|...)
    my(%month)=%{ $Lang{$L}{"MonthH"} };    # { jan=>1, ... }
    my($week)=$Lang{$L}{"Week"};            # (mon|monday|...)
    my(%week)=%{ $Lang{$L}{"WeekH"} };      # { mon=>1, monday=>1, ... }
    my($wom)=$Lang{$L}{"WoM"};              # (1st|...|fifth|last)
    my(%wom)=%{ $Lang{$L}{"WoMH"} };        # { 1st=>1,... fifth=>5,last=>-1 }
    my($dom)=$Lang{$L}{"DoM"};              # (1st|first|...31st)
    my(%dom)=%{ $Lang{$L}{"DoMH"} };        # { 1st=>1, first=>1, ... }
    my($ampmexp)=$Lang{$L}{"AmPm"};         # (am|pm)
    my($timeexp)=$Lang{$L}{"Times"};        # (noon|midnight)
    my($now)=$Lang{$L}{"Now"};              # now
    my($today)=$Lang{$L}{"Today"};          # today
    my($offset)=$Lang{$L}{"Offset"};        # (yesterday|tomorrow)
    my($zone)=$Zone{"zones"};               # (edt|est|...)
    my($day)='\s*'.$Lang{$L}{"Dabb"};       # \s*(?:d|day|days)
    my($mabb)='\s*'.$Lang{$L}{"Mabb"};      # \s*(?:mon|month|months)
    my($wkabb)='\s*'.$Lang{$L}{"Wabb"};     # \s*(?:w|wk|week|weeks)
    my($next)='\s*'.$Lang{$L}{"Next"};      # \s*(?:next)
    my($prev)='\s*'.$Lang{$L}{"Prev"};      # \s*(?:last|previous)
    my($past)='\s*'.$Lang{$L}{"Past"};      # \s*(?:ago)
    my($future)='\s*'.$Lang{$L}{"Future"};  # \s*(?:in)
    my($later)='\s*'.$Lang{$L}{"Later"};    # \s*(?:later)
    my($at)=$Lang{$L}{"At"};                # (?:at)
    my($of)='\s*'.$Lang{$L}{"Of"};          # \s*(?:in|of)
    my($on)='(?:\s*'.$Lang{$L}{"On"}.'\s*|\s+)';
                                            # \s*(?:on)\s*    or  \s+
    my($last)='\s*'.$Lang{$L}{"Last"};      # \s*(?:last)
    my($hm)=$Lang{$L}{"SepHM"};             # :
    my($ms)=$Lang{$L}{"SepMS"};             # :
    my($ss)=$Lang{$L}{"SepSS"};             # .

    # Other regular expressions

    my($D4)='(\d{4})';            	    # 4 digits      (yr)
    my($YY)='(\d{4}|\d{2})';      	    # 2 or 4 digits (yr)
    my($DD)='(\d{2})';            	    # 2 digits      (mon/day/hr/min/sec)
    my($D) ='(\d{1,2})';          	    # 1 or 2 digit  (mon/day/hr)
    my($FS)="(?:$ss\\d+)?";       	    # fractional secs
    my($sep)='[\/.-]';            	    # non-ISO8601 m/d/yy separators