diff --git a/core/attributedef.class.inc.php b/core/attributedef.class.inc.php
index a6642306d..503d26e93 100644
--- a/core/attributedef.class.inc.php
+++ b/core/attributedef.class.inc.php
@@ -5977,7 +5977,7 @@ class AttributeTagSet extends AttributeDBFieldVoid
 	    $aGoodTags = array();
 		foreach($aTagCodes as $sTagCode)
 		{
-			if ($oTagSet->TagsExist($sTagCode))
+			if ($oTagSet->IsValidTag($sTagCode))
 			{
 				$aGoodTags[] = $sTagCode;
 			}
diff --git a/core/cmdbobject.class.inc.php b/core/cmdbobject.class.inc.php
index 1f3694766..8f2cf1485 100644
--- a/core/cmdbobject.class.inc.php
+++ b/core/cmdbobject.class.inc.php
@@ -563,6 +563,12 @@ abstract class CMDBObject extends DBObject
 		$this->DBUpdate();
 	}
 
+	/**
+	 * @param null $oDeletionPlan
+	 *
+	 * @return \DeletionPlan|null
+	 * @throws \DeleteException
+	 */
 	public function DBDelete(&$oDeletionPlan = null)
 	{
 		return $this->DBDeleteTracked_Internal($oDeletionPlan);
@@ -575,6 +581,12 @@ abstract class CMDBObject extends DBObject
 		$this->DBDeleteTracked_Internal($oDeletionPlan);
 	}
 
+	/**
+	 * @param null $oDeletionPlan
+	 *
+	 * @return \DeletionPlan|null
+	 * @throws \DeleteException
+	 */
 	protected function DBDeleteTracked_Internal(&$oDeletionPlan = null)
 	{
 		$prevkey = $this->GetKey();
diff --git a/core/ormtagset.class.inc.php b/core/ormtagset.class.inc.php
index 6a8af77d7..8bc7c1190 100644
--- a/core/ormtagset.class.inc.php
+++ b/core/ormtagset.class.inc.php
@@ -4,7 +4,7 @@
  *
  * This file is part of iTop.
  *
- * iTop is free software; you can redistribute it and/or modify	
+ * iTop is free software; you can redistribute it and/or modify
  * it under the terms of the GNU Affero General Public License as published by
  * the Free Software Foundation, either version 3 of the License, or
  * (at your option) any later version.
@@ -24,160 +24,147 @@
  * Date: 24/08/2018
  * Time: 14:35
  */
-
-
 final class ormTagSet
 {
-    private $sClass; // class of the tag field
-    private $sAttCode; // attcode of the tag field
-    private $aOriginalObjects = null;
+	private $sClass; // class of the tag field
+	private $sAttCode; // attcode of the tag field
+	private $aOriginalObjects = null;
 
-    /**
-     * @var bool
-     */
-    private $bHasDelta = false;
+	/**
+	 * @var bool
+	 */
+	private $bHasDelta = false;
 
-    /**
-     * Object from the original set, minus the removed objects
-     * @var DBObject[] array of iObjectId => DBObject
-     */
-    private $aPreserved = array();
+	/**
+	 * Object from the original set, minus the removed objects
+	 *
+	 * @var DBObject[] array of iObjectId => DBObject
+	 */
+	private $aPreserved = array();
 
-    /**
-     * @var DBObject[] New items
-     */
-    private $aAdded = array();
+	/**
+	 * @var DBObject[] New items
+	 */
+	private $aAdded = array();
 
-    /**
-     * @var DBObject[] Removed items
-     */
-    private $aRemoved = array();
+	/**
+	 * @var DBObject[] Removed items
+	 */
+	private $aRemoved = array();
 
-    /**
-     * __toString magical function overload.
-     */
-    public function __toString()
-    {
-        return '';
-    }
+	/**
+	 * __toString magical function overload.
+	 */
+	public function __toString()
+	{
+		$aValue = $this->GetValue();
+		if (!empty($aValue))
+		{
+			return implode(' ', $aValue);
+		}
+		else
+		{
+			return ' ';
+		}
+	}
 
-    /**
-     * ormTagSet constructor.
-     *
-     * @param string $sClass
-     * @param string $sAttCode
-     *
-     * @throws \Exception
-     */
-    public function __construct($sClass, $sAttCode)
-    {
-        $this->sAttCode = $sAttCode;
+	/**
+	 * ormTagSet constructor.
+	 *
+	 * @param string $sClass
+	 * @param string $sAttCode
+	 *
+	 * @throws \Exception
+	 */
+	public function __construct($sClass, $sAttCode)
+	{
+		$this->sAttCode = $sAttCode;
 
-        $oAttDef = MetaModel::GetAttributeDef($sClass, $sAttCode);
-        if (!$oAttDef instanceof AttributeTagSet)
-        {
-            throw new Exception("ormTagSet: field {$sClass}:{$sAttCode} is not a tag");
-        }
-        $this->sClass = $sClass;
-    }
+		$oAttDef = MetaModel::GetAttributeDef($sClass, $sAttCode);
+		if (!$oAttDef instanceof AttributeTagSet)
+		{
+			throw new Exception("ormTagSet: field {$sClass}:{$sAttCode} is not a tag");
+		}
+		$this->sClass = $sClass;
+	}
 
-    /**
-     *
-     * @param array $aTagCodes
-     *
-     * @throws \CoreException
-     * @throws \CoreUnexpectedValue when a code is invalid
-     */
-    public function SetValue($aTagCodes)
-    {
-        if (!is_array($aTagCodes))
-        {
-            throw new CoreUnexpectedValue("Wrong value {$aTagCodes} for {$this->sClass}:{$this->sAttCode}");
-        }
+	/**
+	 *
+	 * @param array $aTagCodes
+	 *
+	 * @throws \CoreException
+	 * @throws \CoreUnexpectedValue when a code is invalid
+	 */
+	public function SetValue($aTagCodes)
+	{
+		if (!is_array($aTagCodes))
+		{
+			throw new CoreUnexpectedValue("Wrong value {$aTagCodes} for {$this->sClass}:{$this->sAttCode}");
+		}
 
-        $oTags = array();
-        foreach($aTagCodes as $sTagCode)
-        {
-            $oTag = $this->GetTagFromCode($sTagCode);
-            $oTags[$oTag->GetKey()] = $oTag;
-        }
+		$oTags = array();
+		foreach($aTagCodes as $sTagCode)
+		{
+			$oTag = $this->GetTagFromCode($sTagCode);
+			$oTags[$oTag->GetKey()] = $oTag;
+		}
 
-        $this->aPreserved = &$oTags;
-        $this->aRemoved = array();
-        $this->aAdded = array();
-        $this->aOriginalObjects = $oTags;
-        $this->bHasDelta = false;
-    }
+		$this->aPreserved = &$oTags;
+		$this->aRemoved = array();
+		$this->aAdded = array();
+		$this->aOriginalObjects = $oTags;
+		$this->bHasDelta = false;
+	}
 
-    /**
-     * @return array of tag codes
-     */
-    public function GetValue()
-    {
-        $aValues = array();
-        foreach ($this->aPreserved as $oTag)
-        {
-            try
-            {
-                $aValues[] = $oTag->Get('tag_code');
-            } catch (CoreException $e)
-            {
-                IssueLog::Error($e->getMessage());
-            }
-        }
-        foreach ($this->aAdded as $oTag)
-        {
-            try
-            {
-                $aValues[] = $oTag->Get('tag_code');
-            } catch (CoreException $e)
-            {
-                IssueLog::Error($e->getMessage());
-            }
-        }
+	/**
+	 * @return array of tag codes
+	 */
+	public function GetValue()
+	{
+		$aValues = array();
+		foreach($this->aPreserved as $oTag)
+		{
+			try
+			{
+				$aValues[] = $oTag->Get('tag_code');
+			} catch (CoreException $e)
+			{
+				IssueLog::Error($e->getMessage());
+			}
+		}
+		foreach($this->aAdded as $oTag)
+		{
+			try
+			{
+				$aValues[] = $oTag->Get('tag_code');
+			} catch (CoreException $e)
+			{
+				IssueLog::Error($e->getMessage());
+			}
+		}
 
-        sort($aValues);
+		sort($aValues);
 
-        return $aValues;
-    }
+		return $aValues;
+	}
 
 	/**
 	 * @return array of tag labels indexed by code
 	 */
 	public function GetTags()
-    {
-        $aTags = array();
-        foreach ($this->aPreserved as $oTag)
-        {
-            try
-            {
-                $aTags[$oTag->Get('tag_code')] = $oTag->Get('tag_label');
-            } catch (CoreException $e)
-            {
-                IssueLog::Error($e->getMessage());
-            }
-        }
-        foreach ($this->aAdded as $oTag)
-        {
-            try
-            {
-                $aTags[$oTag->Get('tag_code')] = $oTag->Get('tag_label');
-            } catch (CoreException $e)
-            {
-                IssueLog::Error($e->getMessage());
-            }
-        }
-        ksort($aTags);
-        return $aTags;
-    }
-
-	/**
-	 * @return array of tag labels indexed by code for only the added tags
-	 */
-	public function GetAddedTags()
 	{
 		$aTags = array();
-		foreach ($this->aAdded as $oTag)
+		foreach($this->aPreserved as $oTag)
+		{
+			try
+			{
+				$aTags[$oTag->Get('tag_code')] = $oTag->Get('tag_label');
+			} catch (CoreException $e)
+			{
+				IssueLog::Error($e->getMessage());
+			}
+		}
+		foreach($this->aAdded as $oTag)
 		{
 			try
 			{
@@ -188,6 +175,28 @@ final class ormTagSet
 			}
 		}
 		ksort($aTags);
+
+		return $aTags;
+	}
+
+	/**
+	 * @return array of tag labels indexed by code for only the added tags
+	 */
+	public function GetAddedTags()
+	{
+		$aTags = array();
+		foreach($this->aAdded as $oTag)
+		{
+			try
+			{
+				$aTags[$oTag->Get('tag_code')] = $oTag->Get('tag_label');
+			} catch (CoreException $e)
+			{
+				IssueLog::Error($e->getMessage());
+			}
+		}
+		ksort($aTags);
+
 		return $aTags;
 	}
 
@@ -197,7 +206,7 @@ final class ormTagSet
 	public function GetRemovedTags()
 	{
 		$aTags = array();
-		foreach ($this->aRemoved as $oTag)
+		foreach($this->aRemoved as $oTag)
 		{
 			try
 			{
@@ -208,6 +217,7 @@ final class ormTagSet
 			}
 		}
 		ksort($aTags);
+
 		return $aTags;
 	}
 
@@ -222,29 +232,30 @@ final class ormTagSet
 	 *
 	 * @throws \CoreException
 	 * @throws \CoreUnexpectedValue
+	 * @throws \Exception
 	 */
 	public function GetDelta(ormTagSet $oOtherTagSet)
-    {
+	{
 		$oTag = new ormTagSet($this->sClass, $this->sAttCode);
 		// Set the initial value
-	    $aOrigTagCodes = $this->GetValue();
-	    $oTag->SetValue($aOrigTagCodes);
+		$aOrigTagCodes = $this->GetValue();
+		$oTag->SetValue($aOrigTagCodes);
 		// now remove everything
-	    foreach($aOrigTagCodes as $sTagCode)
-	    {
-	    	$oTag->RemoveTag($sTagCode);
-	    }
-	    // now add the tags of the other TagSet
-	    foreach($oOtherTagSet->GetValue() as $sTagCode)
-	    {
-	    	$oTag->AddTag($sTagCode);
-	    }
-	    $aDelta = array();
-	    $aDelta['added'] = $oTag->GetAddedTags();
-	    $aDelta['removed'] = $oTag->GetRemovedTags();
+		foreach($aOrigTagCodes as $sTagCode)
+		{
+			$oTag->RemoveTag($sTagCode);
+		}
+		// now add the tags of the other TagSet
+		foreach($oOtherTagSet->GetValue() as $sTagCode)
+		{
+			$oTag->AddTag($sTagCode);
+		}
+		$aDelta = array();
+		$aDelta['added'] = $oTag->GetAddedTags();
+		$aDelta['removed'] = $oTag->GetRemovedTags();
 
-	    return $aDelta;
-    }
+		return $aDelta;
+	}
 
 	/**
 	 * Apply a delta to the current TagSet
@@ -255,179 +266,195 @@ final class ormTagSet
 	 * @throws \CoreUnexpectedValue
 	 */
 	public function ApplyDelta($aDelta)
-    {
-	    if (isset($aDelta['removed']))
-	    {
-		    foreach($aDelta['removed'] as $sTagCode => $aTagLabel)
-		    {
-			    $this->RemoveTag($sTagCode);
-		    }
-	    }
-	    if (isset($aDelta['added']))
-	    {
-		    foreach($aDelta['added'] as $sTagCode => $aTagLabel)
-		    {
-			    $this->AddTag($sTagCode);
-		    }
-	    }
-    }
+	{
+		if (isset($aDelta['removed']))
+		{
+			foreach($aDelta['removed'] as $sTagCode => $aTagLabel)
+			{
+				$this->RemoveTag($sTagCode);
+			}
+		}
+		if (isset($aDelta['added']))
+		{
+			foreach($aDelta['added'] as $sTagCode => $aTagLabel)
+			{
+				$this->AddTag($sTagCode);
+			}
+		}
+	}
 
 	/**
+	 * Check whether a tag code is valid or not for this TagSet
+	 *
 	 * @param string $sTagCode
 	 *
 	 * @return bool
+	 */
+	public function IsValidTag($sTagCode)
+	{
+		try
+		{
+			$this->GetTagFromCode($sTagCode);
+
+			return true;
+		} catch (Exception $e)
+		{
+			return false;
+		}
+	}
+
+	/**
+	 * @param $sTagCode
+	 *
+	 * @throws \CoreException
+	 * @throws \CoreUnexpectedValue
+	 */
+	public function AddTag($sTagCode)
+	{
+		if ($this->IsTagInList($this->aPreserved, $sTagCode) || $this->IsTagInList($this->aAdded, $sTagCode))
+		{
+			// nothing to do, already existing tag
+			return;
+		}
+		// if removed then added again
+		if (($oTag = $this->RemoveTagFromList($this->aRemoved, $sTagCode)) !== false)
+		{
+			// put it back into preserved
+			$this->aPreserved[] = $oTag;
+		}
+		else
+		{
+			$this->aAdded[] = $this->GetTagFromCode($sTagCode);
+		}
+		$this->UpdateHasDeltaFlag();
+	}
+
+	/**
+	 * @param $sTagCode
+	 */
+	public function RemoveTag($sTagCode)
+	{
+		if ($this->IsTagInList($this->aRemoved, $sTagCode))
+		{
+			// nothing to do, already removed tag
+			return;
+		}
+		// if added then remove it
+		if (($oTag = $this->RemoveTagFromList($this->aAdded, $sTagCode)) === false)
+		{
+			// if present then remove it
+			if (($oTag = $this->RemoveTagFromList($this->aPreserved, $sTagCode)) !== false)
+			{
+				$this->aRemoved[] = $oTag;
+			}
+		}
+		$this->UpdateHasDeltaFlag();
+	}
+
+	private function IsTagInList($aTagList, $sTagCode)
+	{
+		foreach($aTagList as $oTag)
+		{
+			/** @var \TagSetFieldData $oTag */
+			try
+			{
+				$sCode = $oTag->Get('tag_code');
+				if ($sCode === $sTagCode)
+				{
+					return true;
+				}
+			} catch (CoreException $e)
+			{
+				IssueLog::Error($e->getMessage());
+			}
+		}
+
+		return false;
+	}
+
+	private function RemoveTagFromList(&$aTagList, $sTagCode)
+	{
+		foreach($aTagList as $index => $oTag)
+		{
+			/** @var \TagSetFieldData $oTag */
+			try
+			{
+				$sCode = $oTag->Get('tag_code');
+				if ($sCode === $sTagCode)
+				{
+					unset($aTagList[$index]);
+
+					return $oTag;
+				}
+			} catch (CoreException $e)
+			{
+				IssueLog::Error($e->getMessage());
+			}
+		}
+
+		return false;
+	}
+
+	private function UpdateHasDeltaFlag()
+	{
+		if ((count($this->aAdded) == 0) && (count($this->aRemoved) == 0))
+		{
+			$this->bHasDelta = false;
+		}
+		else
+		{
+			$this->bHasDelta = true;
+		}
+	}
+
+
+	/**
+	 * @param $sTagCode
+	 *
+	 * @return DBObject tag
+	 * @throws \CoreUnexpectedValue
 	 * @throws \CoreException
 	 */
-	public function TagsExist($sTagCode)
-    {
-	    try
-	    {
-		    $this->GetTagFromCode($sTagCode);
-		    return true;
-	    } catch (CoreUnexpectedValue $e)
-	    {
-	    	return false;
-	    }
-    }
+	private function GetTagFromCode($sTagCode)
+	{
+		$aAllowedTags = $this->GetAllowedTags();
+		foreach($aAllowedTags as $oAllowedTag)
+		{
+			if ($oAllowedTag->Get('tag_code') === $sTagCode)
+			{
+				return $oAllowedTag;
+			}
+		}
+		throw new CoreUnexpectedValue("{$sTagCode} is not defined as a valid tag for {$this->sClass}:{$this->sAttCode}");
+	}
 
-    /**
-     * @param $sTagCode
-     *
-     * @throws \CoreException
-     * @throws \CoreUnexpectedValue
-     */
-    public function AddTag($sTagCode)
-    {
-        if ($this->IsTagInList($this->aPreserved, $sTagCode) || $this->IsTagInList($this->aAdded, $sTagCode))
-        {
-            // nothing to do, already existing tag
-            return;
-        }
-        // if removed then added again
-        if (($oTag = $this->RemoveTagFromList($this->aRemoved, $sTagCode)) !== false)
-        {
-            // put it back into preserved
-            $this->aPreserved[] = $oTag;
-        }
-        else
-        {
-            $this->aAdded[] = $this->GetTagFromCode($sTagCode);
-        }
-        $this->UpdateHasDeltaFlag();
-    }
+	/**
+	 * @return array
+	 */
+	private function GetAllowedTags()
+	{
+		return TagSetFieldData::GetAllowedValues($this->sClass, $this->sAttCode);
+	}
 
-    /**
-     * @param $sTagCode
-     *
-     * @throws \CoreException
-     * @throws \CoreUnexpectedValue
-     */
-    public function RemoveTag($sTagCode)
-    {
-        if ($this->IsTagInList($this->aRemoved, $sTagCode))
-        {
-            // nothing to do, already removed tag
-            return;
-        }
-        // if added then remove it
-        if (($oTag = $this->RemoveTagFromList($this->aAdded, $sTagCode)) === false)
-        {
-            // if present then remove it
-            if (($oTag = $this->RemoveTagFromList($this->aPreserved, $sTagCode)) !== false)
-            {
-                $this->aRemoved[] = $oTag;
-            }
-        }
-        $this->UpdateHasDeltaFlag();
-    }
+	/**
+	 * Compare Tag Set
+	 *
+	 * @param \ormTagSet $other
+	 *
+	 * @return bool true if same tag set
+	 */
+	public function Equals(ormTagSet $other)
+	{
+		if ($this->GetTagDataClass() !== $other->GetTagDataClass())
+		{
+			return false;
+		}
 
-    private function IsTagInList($aTagList, $sTagCode)
-    {
-        foreach ($aTagList as $oTag)
-        {
-            $sCode = $oTag->Get('tag_code');
-            if ($sCode === $sTagCode)
-            {
-                return true;
-            }
-        }
-        return false;
-    }
+		return implode(' ', $this->GetValue()) === implode(' ', $other->GetValue());
+	}
 
-    private function RemoveTagFromList(&$aTagList, $sTagCode)
-    {
-        foreach ($aTagList as $index => $oTag)
-        {
-            $sCode = $oTag->Get('tag_code');
-            if ($sCode === $sTagCode)
-            {
-                unset($aTagList[$index]);
-                return $oTag;
-            }
-        }
-        return false;
-    }
-
-    private function UpdateHasDeltaFlag()
-    {
-        if ((count($this->aAdded) == 0) && (count($this->aRemoved) == 0))
-        {
-            $this->bHasDelta = false;
-        }
-        else
-        {
-            $this->bHasDelta = true;
-        }
-    }
-
-    /**
-     * @param $sTagCode
-     *
-     * @return DBObject tag
-     * @throws \CoreUnexpectedValue
-     * @throws \CoreException
-     */
-    private function GetTagFromCode($sTagCode)
-    {
-        $aAllowedTags = $this->GetAllowedTags();
-        foreach($aAllowedTags as $oAllowedTag)
-        {
-            if ($oAllowedTag->Get('tag_code') === $sTagCode)
-            {
-                return $oAllowedTag;
-            }
-        }
-        throw new CoreUnexpectedValue("{$sTagCode} is not defined as a valid tag for {$this->sClass}:{$this->sAttCode}");
-    }
-
-    /**
-     * @return array
-     * @throws \CoreException
-     * @throws \Exception
-     */
-    private function GetAllowedTags()
-    {
-       return TagSetFieldData::GetAllowedValues($this->sClass, $this->sAttCode);
-    }
-
-    /**
-     * Compare Tag Set
-     *
-     * @param \ormTagSet $other
-     *
-     * @return bool true if same tag set
-     */
-    public function Equals(ormTagSet $other)
-    {
-        if ($this->GetTagDataClass() !== $other->GetTagDataClass())
-        {
-            return false;
-        }
-        return implode(' ',$this->GetValue()) === implode(' ', $other->GetValue());
-    }
-
-    public function GetTagDataClass()
-    {
-        return MetaModel::GetTagDataClass($this->sClass, $this->sAttCode);
-    }
+	public function GetTagDataClass()
+	{
+		return MetaModel::GetTagDataClass($this->sClass, $this->sAttCode);
+	}
 }
\ No newline at end of file
diff --git a/core/tagsetfield.class.inc.php b/core/tagsetfield.class.inc.php
index 3970d04b5..196e15350 100644
--- a/core/tagsetfield.class.inc.php
+++ b/core/tagsetfield.class.inc.php
@@ -20,8 +20,9 @@
 /**
  * <p>Stores data for {@link AttributeTagSet} fields
  *
- * <p>We will have an implementation for each class/field to be able to customize rights (generated in \MFCompiler::CompileClass).<br>
- * Only this abstract class will exists in the DB : the implementations won't had any new field.
+ * <p>We will have an implementation for each class/field to be able to customize rights (generated in
+ * \MFCompiler::CompileClass).<br> Only this abstract class will exists in the DB : the implementations won't had any
+ * new field.
  *
  * @since 2.6 N°931 tag fields
  */
@@ -29,64 +30,68 @@ abstract class TagSetFieldData extends cmdbAbstractObject
 {
 	private static $m_aAllowedValues = array();
 
-    public static function Init()
-    {
-        $aParams = array
-        (
-            'category' => 'bizmodel',
-            'key_type' => 'autoincrement',
-            'name_attcode' => array('tag_label'),
-            'state_attcode' => '',
-            'reconc_keys' => array('tag_code'),
-            'db_table' => 'priv_tagfielddata',
-            'db_key_field' => 'id',
-            'db_finalclass_field' => 'finalclass',
-        );
+	/**
+	 * @throws \CoreException
+	 * @throws \Exception
+	 */
+	public static function Init()
+	{
+		$aParams = array
+		(
+			'category' => 'bizmodel',
+			'key_type' => 'autoincrement',
+			'name_attcode' => array('tag_label'),
+			'state_attcode' => '',
+			'reconc_keys' => array('tag_code'),
+			'db_table' => 'priv_tagfielddata',
+			'db_key_field' => 'id',
+			'db_finalclass_field' => 'finalclass',
+		);
 
-        MetaModel::Init_Params($aParams);
-        MetaModel::Init_InheritAttributes();
+		MetaModel::Init_Params($aParams);
+		MetaModel::Init_InheritAttributes();
 
-        MetaModel::Init_AddAttribute(new AttributeString("tag_code", array(
-            "allowed_values" => null,
-            "sql" => 'tag_code',
-            "default_value" => '',
-            "is_null_allowed" => false,
-            "depends_on" => array()
-        )));
-        MetaModel::Init_AddAttribute(new AttributeString("tag_label", array(
-            "allowed_values" => null,
-            "sql" => 'tag_label',
-            "default_value" => '',
-            "is_null_allowed" => false,
-            "depends_on" => array()
-        )));
-        MetaModel::Init_AddAttribute(new AttributeString("tag_description", array(
-            "allowed_values" => null,
-            "sql" => 'tag_description',
-            "default_value" => '',
-            "is_null_allowed" => true,
-            "depends_on" => array()
-        )));
-        MetaModel::Init_AddAttribute(new AttributeString("tag_class", array(
-            "allowed_values" => null,
-            "sql" => 'tag_class',
-            "default_value" => '',
-            "is_null_allowed" => false,
-            "depends_on" => array()
-        )));
-        MetaModel::Init_AddAttribute(new AttributeString("tag_attcode", array(
-            "allowed_values" => null,
-            "sql" => 'tag_attcode',
-            "default_value" => '',
-            "is_null_allowed" => false,
-            "depends_on" => array()
-        )));
+		MetaModel::Init_AddAttribute(new AttributeString("tag_code", array(
+			"allowed_values" => null,
+			"sql" => 'tag_code',
+			"default_value" => '',
+			"is_null_allowed" => false,
+			"depends_on" => array()
+		)));
+		MetaModel::Init_AddAttribute(new AttributeString("tag_label", array(
+			"allowed_values" => null,
+			"sql" => 'tag_label',
+			"default_value" => '',
+			"is_null_allowed" => false,
+			"depends_on" => array()
+		)));
+		MetaModel::Init_AddAttribute(new AttributeString("tag_description", array(
+			"allowed_values" => null,
+			"sql" => 'tag_description',
+			"default_value" => '',
+			"is_null_allowed" => true,
+			"depends_on" => array()
+		)));
+		MetaModel::Init_AddAttribute(new AttributeString("tag_class", array(
+			"allowed_values" => null,
+			"sql" => 'tag_class',
+			"default_value" => '',
+			"is_null_allowed" => false,
+			"depends_on" => array()
+		)));
+		MetaModel::Init_AddAttribute(new AttributeString("tag_attcode", array(
+			"allowed_values" => null,
+			"sql" => 'tag_attcode',
+			"default_value" => '',
+			"is_null_allowed" => false,
+			"depends_on" => array()
+		)));
 
 
-        MetaModel::Init_SetZListItems('details', array('tag_code', 'tag_label', 'tag_description'));
-        MetaModel::Init_SetZListItems('standard_search', array('tag_code', 'tag_label', 'tag_description'));
-        MetaModel::Init_SetZListItems('list', array('tag_code', 'tag_label', 'tag_description'));
-    }
+		MetaModel::Init_SetZListItems('details', array('tag_code', 'tag_label', 'tag_description'));
+		MetaModel::Init_SetZListItems('standard_search', array('tag_code', 'tag_label', 'tag_description'));
+		MetaModel::Init_SetZListItems('list', array('tag_code', 'tag_label', 'tag_description'));
+	}
 
 	public function ComputeValues()
 	{
@@ -122,11 +127,30 @@ abstract class TagSetFieldData extends cmdbAbstractObject
 		unset(self::$m_aAllowedValues[$sTagDataClass]);
 	}
 
+	/**
+	 * @throws \CoreException
+	 * @throws \MissingQueryArgument
+	 * @throws \MySQLException
+	 * @throws \MySQLHasGoneAwayException
+	 * @throws \OQLException
+	 */
 	public function DoCheckToWrite()
 	{
 		// Check that code and labels are uniques
 		$sTagCode = $this->Get('tag_code');
+		// Check tag_code syntax
+		if (!preg_match("@^[a-zA-Z0-9]{1,20}$@", $sTagCode))
+		{
+			$this->m_aCheckIssues[] = Dict::S('Core:TagSetFieldData:ErrorTagCodeSyntax');
+		}
+
 		$sTagLabel = $this->Get('tag_label');
+		if (empty($sTagLabel) || (strpos($sTagLabel, "|") !== false))
+		{
+			// Label must not contain | character
+			$this->m_aCheckIssues[] = Dict::S('Core:TagSetFieldData:ErrorTagLabelSyntax');
+		}
+
 		$id = $this->GetKey();
 		$sClassName = get_class($this);
 		if (empty($id))
@@ -151,6 +175,28 @@ abstract class TagSetFieldData extends cmdbAbstractObject
 		parent::DoCheckToWrite();
 	}
 
+	/**
+	 * @throws \CoreException
+	 */
+	public function OnUpdate()
+	{
+		parent::OnUpdate();
+		$aChanges = $this->ListChanges();
+		if (array_key_exists('tag_code', $aChanges))
+		{
+			throw new CoreException(Dict::S('Core:TagSetFieldData:ErrorCodeUpdateNotAllowed'));
+		}
+	}
+
+	/**
+	 * @param $sClass
+	 * @param $sAttCode
+	 *
+	 * @return mixed
+	 * @throws \CoreException
+	 * @throws \CoreUnexpectedValue
+	 * @throws \MySQLException
+	 */
 	public static function GetAllowedValues($sClass, $sAttCode)
 	{
 		$sTagDataClass = MetaModel::GetTagDataClass($sClass, $sAttCode);
@@ -162,6 +208,7 @@ abstract class TagSetFieldData extends cmdbAbstractObject
 			$oSet = new DBObjectSet($oSearch);
 			self::$m_aAllowedValues[$sTagDataClass] = $oSet->ToArray();
 		}
+
 		return self::$m_aAllowedValues[$sTagDataClass];
 	}
 }
\ No newline at end of file
diff --git a/dictionaries/en.dictionary.itop.core.php b/dictionaries/en.dictionary.itop.core.php
index 56776820f..9d64cc960 100644
--- a/dictionaries/en.dictionary.itop.core.php
+++ b/dictionaries/en.dictionary.itop.core.php
@@ -663,7 +663,7 @@ Dict::Add('EN US', 'English', 'English', array(
 	'SynchroDataSource:Definition' => 'Definition',
 	'Core:SynchroAttributes' => 'Attributes',
 	'Core:SynchroStatus' => 'Status',
-	'Core:Synchro:ErrorsLabel' => 'Errors',	
+	'Core:Synchro:ErrorsLabel' => 'Errors',
 	'Core:Synchro:CreatedLabel' => 'Created',
 	'Core:Synchro:ModifiedLabel' => 'Modified',
 	'Core:Synchro:UnchangedLabel' => 'Unchanged',
@@ -690,7 +690,7 @@ Dict::Add('EN US', 'English', 'English', array(
 	'Core:Synchro:label_obj_disappeared_errors' => 'Errors (%1$s)',
 	'Core:Synchro:label_obj_disappeared_no_action' => 'No Action (%1$s)',
 	'Core:Synchro:label_obj_unchanged' => 'Unchanged (%1$s)',
-	'Core:Synchro:label_obj_updated' => 'Updated (%1$s)', 
+	'Core:Synchro:label_obj_updated' => 'Updated (%1$s)',
 	'Core:Synchro:label_obj_updated_errors' => 'Errors (%1$s)',
 	'Core:Synchro:label_obj_new_unchanged' => 'Unchanged (%1$s)',
 	'Core:Synchro:label_obj_new_updated' => 'Updated (%1$s)',
@@ -699,8 +699,8 @@ Dict::Add('EN US', 'English', 'English', array(
 	'Core:SynchroLogTitle' => '%1$s - %2$s',
 	'Core:Synchro:Nb_Replica' => 'Replica processed: %1$s',
 	'Core:Synchro:Nb_Class:Objects' => '%1$s: %2$s',
-	'Class:SynchroDataSource/Error:AtLeastOneReconciliationKeyMustBeSpecified' => 'At Least one reconciliation key must be specified, or the reconciliation policy must be to use the primary key.',			
-	'Class:SynchroDataSource/Error:DeleteRetentionDurationMustBeSpecified' => 'A delete retention period must be specified, since objects are to be deleted after being marked as obsolete',			
+	'Class:SynchroDataSource/Error:AtLeastOneReconciliationKeyMustBeSpecified' => 'At Least one reconciliation key must be specified, or the reconciliation policy must be to use the primary key.',
+	'Class:SynchroDataSource/Error:DeleteRetentionDurationMustBeSpecified' => 'A delete retention period must be specified, since objects are to be deleted after being marked as obsolete',
 	'Class:SynchroDataSource/Error:DeletePolicyUpdateMustBeSpecified' => 'Obsolete objects are to be updated, but no update is specified.',
 	'Class:SynchroDataSource/Error:DataTableAlreadyExists' => 'The table %1$s already exists in the database. Please use another name for the synchro data table.',
 	'Core:SynchroReplica:PublicData' => 'Public Data',
@@ -829,16 +829,16 @@ Dict::Add('EN US', 'English', 'English', array(
 	'Core:ExecProcess:Code255' => 'PHP Error (parsing, or runtime)',
 
 	// Attribute Duration
-	'Core:Duration_Seconds'	=> '%1$ds',	
-	'Core:Duration_Minutes_Seconds'	=>'%1$dmin %2$ds',	
-	'Core:Duration_Hours_Minutes_Seconds' => '%1$dh %2$dmin %3$ds',		
-	'Core:Duration_Days_Hours_Minutes_Seconds' => '%1$sd %2$dh %3$dmin %4$ds',		
+	'Core:Duration_Seconds'	=> '%1$ds',
+	'Core:Duration_Minutes_Seconds'	=>'%1$dmin %2$ds',
+	'Core:Duration_Hours_Minutes_Seconds' => '%1$dh %2$dmin %3$ds',
+	'Core:Duration_Days_Hours_Minutes_Seconds' => '%1$sd %2$dh %3$dmin %4$ds',
 
 	// Explain working time computing
 	'Core:ExplainWTC:ElapsedTime' => 'Time elapsed (stored as "%1$s")',
 	'Core:ExplainWTC:StopWatch-TimeSpent' => 'Time spent for "%1$s"',
 	'Core:ExplainWTC:StopWatch-Deadline' => 'Deadline for "%1$s" at %2$d%%',
-	
+
 	// Bulk export
 	'Core:BulkExport:MissingParameter_Param' => 'Missing parameter "%1$s"',
 	'Core:BulkExport:InvalidParameter_Query' => 'Invalid value for the parameter "query". There is no Query Phrasebook corresponding to the id: "%1$s".',
@@ -914,8 +914,11 @@ Dict::Add('EN US', 'English', 'English', array(
 // Class: TagSetFieldData
 //
 Dict::Add('EN US', 'English', 'English', array(
-    'Class:TagSetFieldData' => 'List of tags',
-    'Class:TagSetFieldData+' => '',
+	'Class:TagSetFieldData' => 'List of tags',
+	'Class:TagSetFieldData+' => '',
 	'Core:TagSetFieldData:ErrorDeleteUsedTag' => 'Used tags cannot be deleted',
 	'Core:TagSetFieldData:ErrorDuplicateTagCodeOrLabel' => 'Tags codes or labels must be unique',
+	'Core:TagSetFieldData:ErrorTagCodeSyntax' => 'Tags code should match [a-zA-Z0-9]{1,20} syntax',
+	'Core:TagSetFieldData:ErrorTagLabelSyntax' => 'Tags label should not contain | nor be empty',
+	'Core:TagSetFieldData:ErrorCodeUpdateNotAllowed' => 'Tags code cannot be changed',
 ));
diff --git a/dictionaries/fr.dictionary.itop.core.php b/dictionaries/fr.dictionary.itop.core.php
index 56c9eb98d..fc7a14f0c 100644
--- a/dictionaries/fr.dictionary.itop.core.php
+++ b/dictionaries/fr.dictionary.itop.core.php
@@ -766,4 +766,7 @@ Opérateurs :<br/>
 	'Core:Validator:MustSelectOne' => 'Veuillez choisir une valeur',
 	'Core:TagSetFieldData:ErrorDeleteUsedTag' => 'Impossible de supprimer une étiquette utilisée',
 	'Core:TagSetFieldData:ErrorDuplicateTagCodeOrLabel' => 'Les codes et noms des étiquettes doivent être unique',
+	'Core:TagSetFieldData:ErrorTagCodeSyntax' => 'Le code de l\'étiquette doit avoir la syntaxe suivante : [a-zA-Z0-9]{1,20}',
+	'Core:TagSetFieldData:ErrorTagLabelSyntax' => 'Le nom de l\'étiquette ne doit pas être vide ni contenir le caractère \'|\'',
+	'Core:TagSetFieldData:ErrorCodeUpdateNotAllowed' => 'Le code de l\'étiquette ne peut pas être changé',
 ));
diff --git a/test/core/TagSetFieldDataTest.php b/test/core/TagSetFieldDataTest.php
index e463e9a4d..689b1eb73 100644
--- a/test/core/TagSetFieldDataTest.php
+++ b/test/core/TagSetFieldDataTest.php
@@ -16,9 +16,12 @@ use TagSetFieldData;
 
 class TagSetFieldDataTest extends ItopDataTestCase
 {
-	// Need commit to create the FULLTEXT INDEX of MySQL
+	// Need database COMMIT in order to create the FULLTEXT INDEX of MySQL
 	const USE_TRANSACTION = false;
 
+	/**
+	 * @throws \CoreException
+	 */
 	public function testGetAllowedValues()
 	{
 		$aAllowedValues = TagSetFieldData::GetAllowedValues(TAG_CLASS, TAG_ATTCODE);
@@ -41,6 +44,9 @@ class TagSetFieldDataTest extends ItopDataTestCase
 		static::assertEquals(4, $iCurrCount - $iInitialCount);
 	}
 
+	/**
+	 * @throws \CoreException
+	 */
 	public function testDoCheckToWrite()
 	{
 		$aAllowedValues = TagSetFieldData::GetAllowedValues(TAG_CLASS, TAG_ATTCODE);
@@ -78,7 +84,7 @@ class TagSetFieldDataTest extends ItopDataTestCase
 
 		try
 		{
-			$this->CreateTagData(TAG_CLASS, TAG_ATTCODE, 'tag5', 'Fourth');
+			$this->CreateTagData(TAG_CLASS, TAG_ATTCODE, 'zembrek', 'Fourth');
 		} catch (\CoreException $e)
 		{
 			$this->debug($e->getMessage());
@@ -91,28 +97,38 @@ class TagSetFieldDataTest extends ItopDataTestCase
 	/**
 	 * @throws \CoreException
 	 * @throws \CoreUnexpectedValue
+	 * @throws \Exception
 	 */
 	public function testDoCheckToDelete()
 	{
 		$oTagData = $this->CreateTagData(TAG_CLASS, TAG_ATTCODE, 'tag1', 'First');
 		$oTagData->DBDelete();
 
+		// Create a tag
 		$oTagData = $this->CreateTagData(TAG_CLASS, TAG_ATTCODE, 'tag1', 'First');
+		//Use it
 		$oTicket = $this->CreateTicket(1);
 		$oTicket->Set(TAG_ATTCODE, 'tag1');
 		$oTicket->DBWrite();
+
+		// Try to delete the tag, must complain !
 		try
 		{
 			$oTagData->DBDelete();
-		}
-		catch (\CoreException $e)
+		} catch (\DeleteException $e)
 		{
 			static::assertTrue(true);
+
 			return;
 		}
+		// Should not pass here
 		static::assertFalse(true);
 	}
 
+	/**
+	 * @throws \CoreException
+	 * @throws \Exception
+	 */
 	public function testComputeValues()
 	{
 		$sTagClass = \MetaModel::GetTagDataClass(TAG_CLASS, TAG_ATTCODE);
@@ -126,4 +142,59 @@ class TagSetFieldDataTest extends ItopDataTestCase
 		static::assertEquals(TAG_ATTCODE, $oTagData->Get('tag_attcode'));
 	}
 
+	/**
+	 * Test invalid tag codes
+	 * @dataProvider InvalidTagCodeProvider
+	 *
+	 * @expectedException \CoreException
+	 *
+	 * @param string $sTagCode
+	 *
+	 * @throws \CoreException
+	 */
+	public function testInvalidTagCode($sTagCode)
+	{
+		$this->CreateTagData(TAG_CLASS, TAG_ATTCODE, $sTagCode, 'First');
+		// Should not pass here
+		static::assertFalse(true);
+	}
+
+	public function InvalidTagCodeProvider()
+	{
+		return array(
+			'No space' => array('tag1 1'),
+			'No _' => array('tag_1'),
+			'No -' => array('tag-1'),
+			'No %' => array('tag%1'),
+			'Less than 21 chars' => array('012345678901234567890'),
+			'At least one char' => array(''),
+			'No #' => array('#tag'),
+			'No !' => array('tag!'),
+		);
+	}
+
+	/**
+	 * Test invalid tag labels
+	 * @expectedException \CoreException
+	 * @throws \CoreException
+	 */
+	public function testInvalidTagLabel()
+	{
+		$this->CreateTagData(TAG_CLASS, TAG_ATTCODE, 'tag1', 'First|Second');
+		// Should not pass here
+		static::assertFalse(true);
+	}
+
+	/**
+	 * Test that tag code cannot be modified
+	 * @expectedException \CoreException
+	 * @throws \CoreException
+	 * @throws \CoreUnexpectedValue
+	 */
+	public function testUpdateCode()
+	{
+		$oTagData = $this->CreateTagData(TAG_CLASS, TAG_ATTCODE, 'tag1', 'First');
+		$oTagData->Set('tag_code', 'tag2');
+		$oTagData->DBWrite();
+	}
 }