diff --git a/core/dict.class.inc.php b/core/dict.class.inc.php
index e3a2a9c8e..0e2cdd466 100644
--- a/core/dict.class.inc.php
+++ b/core/dict.class.inc.php
@@ -20,7 +20,7 @@
  * Class Dict
  * Management of localizable strings 
  *
- * @copyright   Copyright (C) 2010-2012 Combodo SARL
+ * @copyright   Copyright (C) 2010-2018 Combodo SARL
  * @license     http://opensource.org/licenses/AGPL-3.0
  */
 
@@ -65,6 +65,11 @@ class Dict
 	protected static $m_aData = array();
 	protected static $m_sApplicationPrefix = null;
 
+	/**
+	 * @param $sLanguageCode
+	 *
+	 * @throws \DictExceptionUnknownLanguage
+	 */
 	public static function SetDefaultLanguage($sLanguageCode)
 	{
 		if (!array_key_exists($sLanguageCode, self::$m_aLanguages))
@@ -74,6 +79,11 @@ class Dict
 		self::$m_sDefaultLanguage = $sLanguageCode;
 	}
 
+	/**
+	 * @param $sLanguageCode
+	 *
+	 * @throws \DictExceptionUnknownLanguage
+	 */
 	public static function SetUserLanguage($sLanguageCode)
 	{
 		if (!array_key_exists($sLanguageCode, self::$m_aLanguages))
@@ -113,7 +123,6 @@ class Dict
 	 * @param string $sDefault Default value if there is no match in the dictionary
 	 * @param bool $bUserLanguageOnly True to allow the use of the default language as a fallback, false otherwise
 	 *
-	 * @throws DictExceptionMissingString
 	 * @return string
 	 */
 	public static function S($sStringCode, $sDefault = null, $bUserLanguageOnly = false)
@@ -124,7 +133,7 @@ class Dict
 
 		if (!array_key_exists(self::GetUserLanguage(), self::$m_aData))
 		{
-			// It may happen, when something happens before the dictionnaries get loaded
+			// It may happen, when something happens before the dictionaries get loaded
 			return $sStringCode;
 		}
 		$aCurrentDictionary = self::$m_aData[self::GetUserLanguage()];
@@ -155,25 +164,12 @@ class Dict
 		}
 		// Could not find the string...
 		//
-		switch (self::$m_iErrorMode)
+		if (is_null($sDefault))
 		{
-			case DICT_ERR_STRING:
-				if (is_null($sDefault))
-				{
-					return $sStringCode;
-				}
-				else
-				{
-					return $sDefault;
-				}
-				break;
-
-			case DICT_ERR_EXCEPTION:
-			default:
-				throw new DictExceptionMissingString(self::$m_sCurrentLanguage, $sStringCode);
-				break;
+			return $sStringCode;
 		}
-		return 'bug!';
+
+		return $sDefault;
 	}
 
 
@@ -285,6 +281,9 @@ class Dict
 
 	/**
 	 * Clone a string in every language (if it exists in that language)
+	 *
+	 * @param $sSourceCode
+	 * @param $sDestCode
 	 */
 	public static function CloneString($sSourceCode, $sDestCode)
 	{
diff --git a/core/oql/expression.class.inc.php b/core/oql/expression.class.inc.php
index faefb0e25..dd3a73192 100644
--- a/core/oql/expression.class.inc.php
+++ b/core/oql/expression.class.inc.php
@@ -160,7 +160,7 @@ abstract class Expression
 	public function GetCriterion($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
 	{
 		return array(
-			'widget' => AttributeDefinition::SEARCH_WIDGET_TYPE,
+			'widget' => AttributeDefinition::SEARCH_WIDGET_TYPE_RAW,
 			'oql' => $this->Render($aArgs, $bRetrofitParams),
 			'label' => $this->Display($oSearch, $aArgs, $bRetrofitParams, $oAttDef),
 			'source' => get_class($this),
@@ -315,27 +315,6 @@ class BinaryExpression extends Expression
 		return $this->m_sOperator;
 	}
 
-	// recursive rendering
-	public function Display($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
-	{
-		$sOperator = Dict::S($this->GetOperator(), " {$this->GetOperator()} ");
-		$oLeftExpr = $this->GetLeftExpr();
-		if ($oLeftExpr instanceof FieldExpression)
-		{
-			$oAttDef = $oLeftExpr->GetAttDef($oSearch->GetJoinedClasses());
-		}
-		$oRightExpr = $this->GetRightExpr();
-		if ($oRightExpr instanceof FieldExpression)
-		{
-			$oAttDef = $oRightExpr->GetAttDef($oSearch->GetJoinedClasses());
-		}
-
-		$sLeft = $oLeftExpr->Display($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
-		$sRight = $oRightExpr->Display($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
-
-		return "({$sLeft}{$sOperator}{$sRight})";
-	}
-
 	// recursive rendering
 	public function Render(&$aArgs = null, $bRetrofitParams = false)
 	{
@@ -444,6 +423,67 @@ class BinaryExpression extends Expression
 		$this->GetRightExpr()->RenameAlias($sOldName, $sNewName);
 	}
 
+	// recursive rendering
+	public function Display($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
+	{
+		$bReverseOperator = false;
+		$oLeftExpr = $this->GetLeftExpr();
+		if ($oLeftExpr instanceof FieldExpression)
+		{
+			$oAttDef = $oLeftExpr->GetAttDef($oSearch->GetJoinedClasses());
+		}
+		$oRightExpr = $this->GetRightExpr();
+		if ($oRightExpr instanceof FieldExpression)
+		{
+			$oAttDef = $oRightExpr->GetAttDef($oSearch->GetJoinedClasses());
+			$bReverseOperator = true;
+		}
+
+		$sLeft = $oLeftExpr->Display($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
+		$sRight = $oRightExpr->Display($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
+
+		if ($bReverseOperator)
+		{
+			// switch left and right expressions so reverse the operator
+			// Note that the operation is the same so < becomes > and not >=
+			switch ($this->GetOperator())
+			{
+				case '>':
+					$sOperator = '<';
+					break;
+				case '<':
+					$sOperator = '>';
+					break;
+				case '>=':
+					$sOperator = '<=';
+					break;
+				case '<=':
+					$sOperator = '>=';
+					break;
+				default:
+					$sOperator = $this->GetOperator();
+					break;
+			}
+			$sOperator = $this->OperatorToNaturalLanguage($sOperator, $oAttDef);
+
+			return "({$sRight}{$sOperator}{$sLeft})";
+		}
+
+		$sOperator = $this->GetOperator();
+		$sOperator = $this->OperatorToNaturalLanguage($sOperator, $oAttDef);
+
+		return "({$sLeft}{$sOperator}{$sRight})";
+	}
+
+	private function OperatorToNaturalLanguage($sOperator, $oAttDef)
+	{
+		if ($oAttDef instanceof AttributeDateTime)
+		{
+			return Dict::S('Expression:Operator:Date:'.$sOperator, " $sOperator ");
+		}
+
+		return Dict::S('Expression:Operator:'.$sOperator, " $sOperator ");
+	}
 
 	public function GetCriterion($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
 	{
@@ -473,10 +513,10 @@ class BinaryExpression extends Expression
 		$aCriteriaLeft = $oLeftExpr->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
 		$aCriteriaRight = $oRightExpr->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
 
-		$aCriteria = array_merge($aCriteriaLeft, $aCriteriaRight);
 
 		if ($bReverseOperator)
 		{
+			$aCriteria = array_merge($aCriteriaRight, $aCriteriaLeft);
 			// switch left and right expressions so reverse the operator
 			// Note that the operation is the same so < becomes > and not >=
 			switch ($this->GetOperator())
@@ -500,6 +540,7 @@ class BinaryExpression extends Expression
 		}
 		else
 		{
+			$aCriteria = array_merge($aCriteriaLeft, $aCriteriaRight);
 			$aCriteria['operator'] = $this->GetOperator();
 		}
 		$aCriteria['oql'] = $this->Render($aArgs, $bRetrofitParams);
@@ -598,7 +639,7 @@ class ScalarExpression extends UnaryExpression
 	 * @param AttributeDefinition $oAttDef
 	 *
 	 * @return array|string
-	 * @throws Exception
+	 * @throws \Exception
 	 */
 	public function Display($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
 	{
@@ -748,7 +789,9 @@ class FieldExpression extends UnaryExpression
 	 * @param AttributeDefinition $oAttDef
 	 *
 	 * @return array|string
-	 * @throws Exception
+	 * @throws \CoreException
+	 * @throws \DictExceptionMissingString
+	 * @throws \Exception
 	 */
 	public function Display($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
 	{
@@ -1458,6 +1501,60 @@ class FunctionExpression extends Expression
 		}
 		return $sRes;
 	}
+
+	public function Display($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
+	{
+		if ($this->m_sVerb != 'DATE_SUB' && $this->m_sVerb != 'DATE_ADD' && $this->m_sVerb != 'NOW')
+		{
+			return $this->Render($aArgs, $bRetrofitParams);
+		}
+		$sOperation = '';
+		switch ($this->m_sVerb)
+		{
+			case 'NOW':
+				$sOperation = '';
+				break;
+			case 'DATE_SUB':
+				$sOperation = '-';
+				break;
+			case 'DATE_ADD':
+				$sOperation = '+';
+				break;
+		}
+
+		foreach($this->m_aArgs as $oExpression)
+		{
+			$sOperation .= $oExpression->Display($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
+		}
+
+		return $sOperation;
+	}
+
+	public function GetCriterion($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
+	{
+		if ($this->m_sVerb != 'DATE_SUB' && $this->m_sVerb != 'DATE_ADD' && $this->m_sVerb != 'NOW')
+		{
+			return parent::GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
+		}
+
+		$aCriteria = array('widget' => 'date_time');
+
+		foreach($this->m_aArgs as $oExpression)
+		{
+			$aCriteria = array_merge($oExpression->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef), $aCriteria);
+		}
+
+		if ($this->m_sVerb == 'NOW')
+		{
+			$aCriteria['is_relative'] = true;
+		}
+		else
+		{
+			$aCriteria['verb'] = $this->m_sVerb;
+		}
+
+		return $aCriteria;
+	}
 }
 
 class IntervalExpression extends Expression
@@ -1544,6 +1641,19 @@ class IntervalExpression extends Expression
 	{
 		$this->m_oValue->RenameAlias($sOldName, $sNewName);
 	}
+
+	public function GetCriterion($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
+	{
+		$aCriteria = $this->m_oValue->GetCriterion($oSearch, $aArgs, $bRetrofitParams, $oAttDef);
+		$aCriteria['unit'] = $this->m_sUnit;
+
+		return $aCriteria;
+	}
+
+	public function Display($oSearch, &$aArgs = null, $bRetrofitParams = false, $oAttDef = null)
+	{
+		return $this->m_oValue->Render($aArgs, $bRetrofitParams).' '.$this->m_sUnit;
+	}
 }
 
 class CharConcatExpression extends Expression
diff --git a/dictionaries/en.dictionary.itop.ui.php b/dictionaries/en.dictionary.itop.ui.php
index 8c901c0f7..5f69811ca 100644
--- a/dictionaries/en.dictionary.itop.ui.php
+++ b/dictionaries/en.dictionary.itop.ui.php
@@ -311,6 +311,17 @@ Dict::Add('EN US', 'English', 'English', array(
 	'Class:URP_AttributeGrant/Attribute:attcode+' => 'attribute code',
 ));
 
+//
+// Expression to Natural language
+//
+Dict::Add('EN US', 'English', 'English', array(
+	'Expression:Unit:Short:DAY' => 'd',
+	'Expression:Unit:Short:WEEK' => 'w',
+	'Expression:Unit:Short:MONTH' => 'm',
+	'Expression:Unit:Short:YEAR' => 'y',
+));
+
+
 //
 // String from the User Interface: menu, messages, buttons, etc...
 //
diff --git a/dictionaries/fr.dictionary.itop.ui.php b/dictionaries/fr.dictionary.itop.ui.php
index c440b27aa..afc3544f8 100644
--- a/dictionaries/fr.dictionary.itop.ui.php
+++ b/dictionaries/fr.dictionary.itop.ui.php
@@ -1219,4 +1219,17 @@ Lors de l\'association à un déclencheur, on attribue à chaque action un numé
 	'UI:Search:Criteria:Title:String:StartsWith' => '%1$s commence par %2$s',
 	'UI:Search:Criteria:Title:String:EndsWith' => '%1$s fini par %2$s',
 	'UI:Search:Criteria:Title:Enum:In' => '%1$s parmi %2$s',
-));
\ No newline at end of file
+));
+
+
+//
+// Expression to Natural language
+//
+Dict::Add('FR FR', 'French', 'Français', array(
+	'Expression:Operator:AND' => 'ET',
+	'Expression:Operator:OR' => 'OU',
+	'Expression:Unit:Short:DAY' => 'j',
+	'Expression:Unit:Short:WEEK' => 's',
+	'Expression:Unit:Short:MONTH' => 'm',
+	'Expression:Unit:Short:YEAR' => 'a',
+));
diff --git a/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php b/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php
index 24ce40b57..73ff8ffb4 100644
--- a/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php
+++ b/sources/application/search/criterionconversion/criteriontosearchform.class.inc.php
@@ -30,10 +30,17 @@ use AttributeDefinition;
 use Combodo\iTop\Application\Search\CriterionConversionAbstract;
 use DateInterval;
 use DateTime;
+use Dict;
 
 class CriterionToSearchForm extends CriterionConversionAbstract
 {
 
+	/**
+	 * @param array $aAndCriterionRaw
+	 * @param array $aFieldsByCategory
+	 *
+	 * @return array
+	 */
 	public static function Convert($aAndCriterionRaw, $aFieldsByCategory)
 	{
 		$aAllFields = array();
@@ -50,6 +57,8 @@ class CriterionToSearchForm extends CriterionConversionAbstract
 		$aMappingOperatorToFunction = array(
 			AttributeDefinition::SEARCH_WIDGET_TYPE_STRING => 'TextToSearchForm',
 			AttributeDefinition::SEARCH_WIDGET_TYPE_ENUM => 'EnumToSearchForm',
+			AttributeDefinition::SEARCH_WIDGET_TYPE_DATE => 'DateToSearchForm',
+			AttributeDefinition::SEARCH_WIDGET_TYPE_DATE_TIME => 'DateTimeToSearchForm',
 		);
 
 		foreach($aAndCriterionRaw as $aCriteria)
@@ -181,6 +190,7 @@ class CriterionToSearchForm extends CriterionConversionAbstract
 		$aCurrCriterion['values'][] = array('value' => $sLastDate, 'label' => $sLastDate);
 
 		$aCurrCriterion['oql'] = "({$aPrevCriterion['oql']} AND {$aCurrCriterion['oql']})";
+		$aCurrCriterion['label'] = $aPrevCriterion['label'].' '.Dict::S('Expression:Operator:AND', 'AND').' '.$aCurrCriterion['label'];
 
 		$aMergedCriterion[] = $aCurrCriterion;
 
@@ -236,6 +246,7 @@ class CriterionToSearchForm extends CriterionConversionAbstract
 		$aCurrCriterion['values'][] = array('value' => $sLastDate, 'label' => $sLastDate);
 
 		$aCurrCriterion['oql'] = "({$aPrevCriterion['oql']} AND {$aCurrCriterion['oql']})";
+		$aCurrCriterion['label'] = $aPrevCriterion['label'].' '.Dict::S('Expression:Operator:AND', 'AND').' '.$aCurrCriterion['label'];
 
 		$aMergedCriterion[] = $aCurrCriterion;
 
@@ -323,4 +334,44 @@ class CriterionToSearchForm extends CriterionConversionAbstract
 
 		return $aCriteria;
 	}
+
+	protected static function DateToSearchForm($aCriteria, $aFields)
+	{
+		return DateTimeToSearchForm($aCriteria, $aFields);
+	}
+
+	protected static function DateTimeToSearchForm($aCriteria, $aFields)
+	{
+		if (!array_key_exists('is_relative', $aCriteria) || !$aCriteria['is_relative'])
+		{
+			return $aCriteria;
+		}
+
+		if (isset($aCriteria['values'][0]['value']))
+		{
+			$sLabel = $aCriteria['values'][0]['value'];
+			if (isset($aCriteria['verb']))
+			{
+				switch ($aCriteria['verb'])
+				{
+					case 'DATE_SUB':
+						$sLabel = '-'.$sLabel;
+						break;
+					case 'DATE_ADD':
+						$sLabel = '+'.$sLabel;
+						break;
+				}
+			}
+			if (isset($aCriteria['unit']))
+			{
+				$sLabel .= Dict::S('Expression:Unit:Short:'.$aCriteria['unit'], $aCriteria['unit']);
+			}
+			$aCriteria['values'][0]['label'] = $sLabel;
+		}
+
+		// Temporary until the JS widget support relative dates
+		$aCriteria['widget'] = AttributeDefinition::SEARCH_WIDGET_TYPE_RAW;
+
+		return $aCriteria;
+	}
 }
\ No newline at end of file