diff --git a/lib/PGcore.pm b/lib/PGcore.pm
index 93b9fbb025..dd67cda465 100644
--- a/lib/PGcore.pm
+++ b/lib/PGcore.pm
@@ -936,4 +936,4 @@ sub surePathToTmpFile {
 }
 
 
-1;
\ No newline at end of file
+1;
diff --git a/lib/Parser/Context/Constants.pm b/lib/Parser/Context/Constants.pm
index 2fcd96ba0c..344bfea00e 100644
--- a/lib/Parser/Context/Constants.pm
+++ b/lib/Parser/Context/Constants.pm
@@ -11,7 +11,7 @@ sub init {
   $self->{dataName} = 'constants';
   $self->{name} = 'constant';
   $self->{Name} = 'Constant';
-  $self->{namePattern} = qr/[a-zA-Z][a-zA-Z0-9]*|_blank_/;
+  $self->{namePattern} = qr/[a-zA-Z][a-zA-Z0-9]*|_blank_|_0/;
   $self->{tokenType} = 'const';
 }
 
diff --git a/lib/Parser/Context/Default.pm b/lib/Parser/Context/Default.pm
index 775f20483e..694609d569 100644
--- a/lib/Parser/Context/Default.pm
+++ b/lib/Parser/Context/Default.pm
@@ -133,10 +133,11 @@ $lists = {
 
 $constants = {
    'e'  => exp(1),
-   'pi' => 4*atan2(1,1),
-   'i'  => Value::Complex->new(0,1),
-   'j'  => Value::Vector->new(0,1,0)->with(ijk=>1),
-   'k'  => Value::Vector->new(0,0,1)->with(ijk=>1),
+   'pi' => {value => 4*atan2(1,1), TeX => '\pi ', perl => "pi"},
+   'i'  => {value => Value::Complex->new(0,1), isConstant => 1,                        string => "i", perl => "i"},
+   'j'  => {value => Value::Vector->new(0,1,0)->with(ijk=>1), TeX => '\boldsymbol{j}', string => "j", perl => "j"},
+   'k'  => {value => Value::Vector->new(0,0,1)->with(ijk=>1), TeX => '\boldsymbol{k}', string => "k", perl => "k"},
+   '_0' => {value => Value::Vector->new(0,0,0), hidden => 1,  TeX => '\boldsymbol{0}', string => "0"},
    '_blank_' => {value => 0, hidden => 1, string => "", TeX => ""},
 };
 
@@ -264,13 +265,6 @@ $context = $context{Full} = new Parser::Context(
   reduction => $Parser::reduce,
 );
 
-$context->constants->set(
-  pi => {TeX => '\pi ', perl => 'pi'},
-  i => {isConstant => 1, perl => 'i'},
-  j => {TeX => '\boldsymbol{j}', perl => 'j'},
-  k => {TeX => '\boldsymbol{k}', perl => 'k'},
-);
-
 $context->usePrecedence('Standard');
 $context->{name} = "Full";
 
@@ -296,18 +290,16 @@ $context->{name} = "Numeric";
 $context = $context{Vector} = $context{Full}->copy;
 $context->variables->are(x=>'Real',y=>'Real',z=>'Real');
 $context->functions->undefine('arg','mod','Re','Im','conj');
-$context->constants->replace(i=>Value::Vector->new(1,0,0)->with(ijk=>1));
-$context->constants->set(i=>{TeX=>'\boldsymbol{i}', perl=>'i'});
+$context->constants->set(
+  i => {value => Value::Vector->new(1,0,0)->with(ijk=>1), TeX => '\boldsymbol{i}'},
+);
 $context->parens->set('(' => {formMatrix => 0});
 
 $context = $context{Vector2D} = $context{Vector}->copy;
-$context->constants->replace(
-  i => Value::Vector->new(1,0)->with(ijk=>1),
-  j => Value::Vector->new(0,1)->with(ijk=>1),
-);
 $context->constants->set(
-  i => {TeX=>'\boldsymbol{i}', perl=>'i'},
-  j => {TeX=>'\boldsymbol{j}', perl=>'j'}
+  i => {value => Value::Vector->new(1,0)->with(ijk=>1)},
+  j => {value => Value::Vector->new(0,1)->with(ijk=>1)},
+  '_0' => {value => Value::Vector->new(0,0)},
 );
 $context->constants->remove("k");
 $context->{name} = "Vector2D";
@@ -318,7 +310,7 @@ $context->{name} = "Vector2D";
 $context = $context{Point} = $context{Vector}->copy;
 $context->operators->undefine("><",".");
 $context->functions->undefine('norm','unit');
-$context->constants->remove('i','j','k');
+$context->constants->remove('i','j','k','_0');
 $context->parens->remove("<");
 $context->{name} = "Point";
 
diff --git a/lib/Parser/List/Vector.pm b/lib/Parser/List/Vector.pm
index e76c40c7ee..23d2a96cb5 100644
--- a/lib/Parser/List/Vector.pm
+++ b/lib/Parser/List/Vector.pm
@@ -24,40 +24,42 @@ sub _check {
   }
 }
 
-my $ijk_string = ['i','j','k','0'];
-my $ijk_TeX = ['\boldsymbol{i}','\boldsymbol{j}','\boldsymbol{k}','\boldsymbol(0)'];
-
 sub ijk {
-  my $self = shift;
-  my $method = shift || 'TeX'; my $ijk = shift || $ijk_TeX;
+  my $self = shift; my $method = shift || 'string';
   my @coords = @{$self->{coords}};
   $self->Error("Method 'ijk' can only be used on vectors in three-space")
     unless (scalar(@coords) <= 3);
+  my @ijk = (); my $constants = $self->context->{constants};
+  foreach my $x ('i','j','k','_0') {
+    my $v = (split(//,$x))[-1];
+    push(@ijk,($constants->{$x}||{string=>$v,TeX=>"\\boldsymbol{$v}"})->{$method});
+  }
   my $prec = $self->{equation}{context}->operators->get('*')->{precedence};
   my $string = ''; my $n; my $term;
   foreach $n (0..scalar(@coords)-1) {
     $term = $coords[$n]->$method($prec);
     if ($term ne '0') {
+      $term =~ s/\((-(\d+(\.\d*)?|\.\d+))\)/\1/;
       $term = '' if $term eq '1'; $term = '-' if $term eq '-1';
       $term = '+' . $term unless $string eq '' or $term =~ m/^-/;
-      $string .= $term . $ijk->[$n];
+      $string .= $term . $ijk[$n];
     }
   }
-  $string = $ijk->[3] if $string eq '';
+  $string = $ijk[3] if $string eq '';
   return $string;
 }
 
 sub TeX {
   my $self = shift;
-  if ($self->{ijk} || $self->{equation}{ijk} || $self->{equation}{context}->flag("ijk")) 
-    {return $self->ijk}
+  return $self->ijk("TeX")
+    if $self->{ijk} || $self->{equation}{ijk} || $self->{equation}{context}->flag("ijk");
   return $self->SUPER::TeX;
 }
 
 sub string {
   my $self = shift;
-  if ($self->{ijk} || $self->{equation}{ijk} || $self->{equation}{context}->flag("ijk")) 
-    {return $self->ijk('string',$ijk_string)}
+  return $self->ijk("string")
+    if $self->{ijk} || $self->{equation}{ijk} || $self->{equation}{context}->flag("ijk");
   return $self->SUPER::string;
 }
 
diff --git a/lib/Parser/Value.pm b/lib/Parser/Value.pm
index e1a391074e..dc7efb4a80 100644
--- a/lib/Parser/Value.pm
+++ b/lib/Parser/Value.pm
@@ -33,6 +33,7 @@ sub new {
   $type = $context->Package($type), $value = $type->new($context,@{$value}) unless $type eq 'value';
   $type = $value->typeRef;
 
+  $value->inContext($context);  # force context to be the equation's context
   my $c = bless {
     value => $value, type => $type, isConstant => 1,
     ref => $ref, equation => $equation,
diff --git a/lib/Value/Vector.pm b/lib/Value/Vector.pm
index 40b4000a6b..1d4d97add7 100644
--- a/lib/Value/Vector.pm
+++ b/lib/Value/Vector.pm
@@ -236,15 +236,6 @@ sub areParallel {(shift)->isParallel(@_)}
 #  Generate the various output formats
 #
 
-my $ijk_string = ['i','j','k','0'];
-my $ijk_TeX = ['\boldsymbol{i}','\boldsymbol{j}','\boldsymbol{k}','\boldsymbol{0}'];
-
-sub string {
-  my $self = shift; my $equation = shift;
-  return $self->ijk($ijk_string) if $self->getFlag("ijk") && !$self->{ColumnVector};
-  return $self->SUPER::string($equation,@_);
-}
-
 sub pdot {
   my $self = shift;
   my $string = $self->string;
@@ -253,6 +244,12 @@ sub pdot {
   return $string;
 }
 
+sub string {
+  my $self = shift; my $equation = shift;
+  return $self->ijk("string") if $self->getFlag("ijk") && !$self->{ColumnVector};
+  return $self->SUPER::string($equation,@_);
+}
+
 sub TeX {
   my $self = shift; my $equation = shift;
   if ($self->{ColumnVector}) {
@@ -270,21 +267,20 @@ sub TeX {
     }
     return $open.'\begin{array}{c}'.join('\\\\',@coords).'\\\\\end{array}'.$close;
   }
-  return $self->ijk if $self->getFlag("ijk");
+  return $self->ijk("TeX") if $self->getFlag("ijk");
   return $self->SUPER::TeX($equation,@_);
 }
 
 sub ijk {
-  my $self = shift; my $ijk = shift;
-  if (!$ijk) {
-    my $context = $self->context;
-    $ijk = []; $ijk->[3] = $ijk_TeX->[3];
-    foreach my $i (0,1,2)
-      {$ijk->[$i] = $context->{constants}{$ijk_string->[$i]}{TeX} || $ijk_TeX->[$i]}
-  }
+  my $self = shift; my $type = shift || "string";
   my @coords = @{$self->data};
   Value::Error("Method 'ijk' can only be used on Vectors in 3-space")
     unless (scalar(@coords) <= 3);
+  my @ijk = (); my $constants = $self->context->{constants};
+  foreach my $x ('i','j','k','_0') {
+    my $v = (split(//,$x))[-1];
+    push(@ijk,($constants->{$x}||{string=>$v,TeX=>"\\boldsymbol{$v}"})->{$type});
+  }
   my $string = ''; my $n; my $term;
   foreach $n (0..scalar(@coords)-1) {
     $term = $coords[$n]; $term = (Value::isValue($term))? $term->string : "$term";
@@ -292,10 +288,10 @@ sub ijk {
       $term = '' if $term eq '1'; $term = '-' if $term eq '-1';
       $term = '('.$term.')' if $term =~ m/e/i;
       $term = '+' . $term unless $string eq '' or $term =~ m/^-/;
-      $string .= $term . $ijk->[$n];
+      $string .= $term . $ijk[$n];
     }
   }
-  $string = $ijk->[3] if $string eq '';
+  $string = $ijk[3] if $string eq '';
   return $string;
 }
 
diff --git a/macros/PGbasicmacros.pl b/macros/PGbasicmacros.pl
index cf4b40e11b..df27b776c2 100644
--- a/macros/PGbasicmacros.pl
+++ b/macros/PGbasicmacros.pl
@@ -29,7 +29,10 @@ =head1 DESCRIPTION
 
 =cut
 
-# this is equivalent to use strict, but can be used within the Safe compartment.
+sub _PGbasicmacros_init { }
+
+# this is equivalent to use strict, but can be used within the Safe compartmen
+
 BEGIN{
 	be_strict;
 }
@@ -353,6 +356,9 @@ sub NAMED_ANS_RULE {
 
         # end of addition for dragmath
 
+	# try to escape HTML entities to deal with xss stuff
+	$answer_value = HTML::Entities::encode_entities($answer_value);
+
 	MODES(
 		TeX => "\\mbox{\\parbox[t]{${tcol}ex}{\\hrulefill}}",
 		Latex2HTML => qq!\\begin{rawhtml}<INPUT TYPE=TEXT SIZE=$col NAME=\"$name\" VALUE = \"\">\\end{rawhtml}!,
@@ -443,6 +449,8 @@ sub ANS_RULE {  #deprecated
 	$name = RECORD_ANS_NAME($name, $answer_value);
 	$answer_value =~ tr/\\$@`//d;   #`## make sure student answers can not be interpolated by e.g. EV3
 	#INSERT_RESPONSE($name,$name,$answer_value); # no longer needed?
+	# try to escape HTML entities to deal with xss stuff
+	$answer_value = HTML::Entities::encode_entities($answer_value);
 	my $out = MODES(
 	     TeX => qq!\\vskip $height in \\hrulefill\\quad !,
 	     Latex2HTML => qq!\\begin{rawhtml}<TEXTAREA NAME="$name" id="$name" ROWS="$row" COLS="$col"
@@ -946,6 +954,7 @@ sub NAMED_ANS_ARRAY_EXTENSION{
 
 	$answer_value =~ tr/\\$@`//d;   #`## make sure student answers can not be interpolated by e.g. EV3
 #	warn "ans_label $options{ans_label} $name $answer_value";
+	$answer_value = HTML::Entities::encode_entities($answer_value);
 	if (defined($options{ans_label}) ) {
 		INSERT_RESPONSE($options{ans_label}, $name, $answer_value);
 	}
diff --git a/macros/PGessaymacros.pl b/macros/PGessaymacros.pl
index e0f5b4dd67..c0fc79d064 100644
--- a/macros/PGessaymacros.pl
+++ b/macros/PGessaymacros.pl
@@ -57,8 +57,13 @@ sub essay_cmp {
 	my %response_options = @_;
 	### the answer needs to be sanitized.  It could currently contain badness written 
 	### into the answer by the student
-
-	my $scrubber = HTML::Scrubber->new();
+	my $scrubber = HTML::Scrubber->new(
+	    default=> 1,
+	    script => 0,
+	    process => 0,
+	    comment => 0
+	    );
+	
 	$student->{original_student_ans} = $scrubber->scrub($student->{original_student_ans});
 
 	# always returns false but stuff should check for the essay flag and avoid the red highlighting