diff --git a/CloudObjects/SDK/COIDParser.php b/CloudObjects/SDK/COIDParser.php
index c270668..0fb4aae 100644
--- a/CloudObjects/SDK/COIDParser.php
+++ b/CloudObjects/SDK/COIDParser.php
@@ -13,140 +13,140 @@ use ML\IRI\IRI;
  */
 class COIDParser {
 
-  const COID_INVALID = 0;
+    const COID_INVALID = 0;
 
-  const COID_ROOT = 1;
-  const COID_UNVERSIONED = 2;
-  const COID_VERSIONED = 3;
-  const COID_VERSION_WILDCARD = 4;
+    const COID_ROOT = 1;
+    const COID_UNVERSIONED = 2;
+    const COID_VERSIONED = 3;
+    const COID_VERSION_WILDCARD = 4;
 
-  const REGEX_HOSTNAME = "/^([a-z0-9-]+\.)?[a-z0-9-]+\.[a-z]+$/";
-  const REGEX_SEGMENT = "/^[A-Za-z-_0-9\.]+$/";
-  const REGEX_VERSION_WILDCARD = "/^((\^|~)(\d+\.)?\d|(\d+\.){1,2}\*)$/";
+    const REGEX_HOSTNAME = "/^([a-z0-9-]+\.)?[a-z0-9-]+\.[a-z]+$/";
+    const REGEX_SEGMENT = "/^[A-Za-z-_0-9\.]+$/";
+    const REGEX_VERSION_WILDCARD = "/^((\^|~)(\d+\.)?\d|(\d+\.){1,2}\*)$/";
 
-  /**
-   * Creates a new IRI object representing a COID from a string.
-   * Adds the "coid://" prefix if necessary and normalizes case.
-   *
-   * @param string $coidString A COID string.
-   * @return IRI
-   */
-  public static function fromString($coidString) {
-    $coidPre = new IRI(
-      (strtolower(substr($coidString, 0, 7))=='coid://') ? $coidString : 'coid://'.$coidString
-    );
-    // Normalize scheme and host segments to lower case
-    return new IRI('coid://'.strtolower($coidPre->getHost()).$coidPre->getPath());
-  }
-
-  /**
-   * Get the type of a COID.
-   *
-   * @param IRI $coid
-   * @return int|null
-   */
-  public static function getType(IRI $coid) {
-    if ($coid->getScheme()!='coid' || $coid->getHost()==''
-        || preg_match(self::REGEX_HOSTNAME, $coid->getHost()) != 1)
-      return self::COID_INVALID;
-
-    if ($coid->getPath()=='' || $coid->getPath()=='/')
-      return self::COID_ROOT;
-
-    $segments = explode('/', $coid->getPath());
-    switch (count($segments)) {
-      case 2:
-        return (preg_match(self::REGEX_SEGMENT, $segments[1]) == 1)
-          ? self::COID_UNVERSIONED
-          : self::COID_INVALID;
-      case 3:
-        if (preg_match(self::REGEX_SEGMENT, $segments[1]) != 1)
-          return self::COID_INVALID;
-
-        if (preg_match(self::REGEX_SEGMENT, $segments[2]) == 1)
-          return self::COID_VERSIONED;
-        else
-        if (preg_match(self::REGEX_VERSION_WILDCARD, $segments[2]) == 1)
-          return self::COID_VERSION_WILDCARD;
-        else
-          return self::COID_INVALID;
-      default:
-        return self::COID_INVALID;
+    /**
+     * Creates a new IRI object representing a COID from a string.
+     * Adds the "coid://" prefix if necessary and normalizes case.
+     *
+     * @param string $coidString A COID string.
+     * @return IRI
+     */
+    public static function fromString($coidString) : IRI {
+        $coidPre = new IRI(
+            (strtolower(substr($coidString, 0, 7)) == 'coid://') ? $coidString : 'coid://'.$coidString
+        );
+        // Normalize scheme and host segments to lower case
+        return new IRI('coid://'.strtolower($coidPre->getHost()).$coidPre->getPath());
     }
-  }
 
-  /**
-   * Checks whether the given IRI object is a valid COID.
-   *
-   * @param IRI $coid
-   * @return boolean
-   */
-  public static function isValidCOID(IRI $coid) {
-    return (self::getType($coid)!=self::COID_INVALID);
-  }
+    /**
+     * Get the type of a COID.
+     *
+     * @param IRI $coid
+     * @return int|null
+     */
+    public static function getType(IRI $coid) : ?int {
+        if ($coid->getScheme()!='coid' || $coid->getHost()==''
+                || preg_match(self::REGEX_HOSTNAME, $coid->getHost()) != 1)
+            return self::COID_INVALID;
 
-  /**
-   * Get the name segment of a valid COID or null if not available.
-   *
-   * @param IRI $coid
-   * @return string|null
-   */
-  public static function getName(IRI $coid) {
-    if (self::getType($coid)!=self::COID_INVALID
-        && self::getType($coid)!=self::COID_ROOT) {
-      $segments = explode('/', $coid->getPath());
-      return $segments[1];
-    } else
-      return null;
-  }
+        if ($coid->getPath()=='' || $coid->getPath()=='/')
+            return self::COID_ROOT;
 
-  /**
-   * Get the version segment of a valid, versioned COID or null if not available.
-   *
-   * @param IRI $coid
-   * @return string|null
-   */
-  public static function getVersion(IRI $coid) {
-    if (self::getType($coid)==self::COID_VERSIONED) {
-      $segments = explode('/', $coid->getPath());
-      return $segments[2];
-    } else
-      return null;
-  }
+        $segments = explode('/', $coid->getPath());
+        switch (count($segments)) {
+        case 2:
+            return (preg_match(self::REGEX_SEGMENT, $segments[1]) == 1)
+                ? self::COID_UNVERSIONED
+                : self::COID_INVALID;
+            case 3:
+                if (preg_match(self::REGEX_SEGMENT, $segments[1]) != 1)
+                    return self::COID_INVALID;
 
-  /**
-   * Get the version segment of a versioned or version wildcard COID or
-   * null if not available.
-   *
-   * @param IRI $coid
-   * @return string|null
-   */
-  public static function getVersionWildcard(IRI $coid) {
-    if (self::getType($coid)==self::COID_VERSION_WILDCARD) {
-      $segments = explode('/', $coid->getPath());
-      return $segments[2];
-    } else
-      return null;
-  }
-
-  /**
-   * Returns the COID itself if it is a root COID or a new IRI object
-   * representing the namespace underlying the given COID.
-   *
-   * @param IRI $coid
-   * @return IRI|null
-   */
-  public static function getNamespaceCOID(IRI $coid) {
-    switch (self::getType($coid)) {
-      case self::COID_ROOT:
-        return $coid;
-      case self::COID_UNVERSIONED:
-      case self::COID_VERSIONED:
-      case self::COID_VERSION_WILDCARD:
-        return new IRI('coid://'.$coid->getHost());
-      default:
-        return null;
+                if (preg_match(self::REGEX_SEGMENT, $segments[2]) == 1)
+                    return self::COID_VERSIONED;
+                else
+                if (preg_match(self::REGEX_VERSION_WILDCARD, $segments[2]) == 1)
+                    return self::COID_VERSION_WILDCARD;
+                else
+                    return self::COID_INVALID;
+            default:
+                return self::COID_INVALID;
+        }
+    }
+
+    /**
+     * Checks whether the given IRI object is a valid COID.
+     *
+     * @param IRI $coid
+     * @return bool
+     */
+    public static function isValidCOID(IRI $coid) : bool {
+        return (self::getType($coid)!=self::COID_INVALID);
+    }
+
+    /**
+     * Get the name segment of a valid COID or null if not available.
+     *
+     * @param IRI $coid
+     * @return string|null
+     */
+    public static function getName(IRI $coid) : ?string {
+        if (self::getType($coid)!=self::COID_INVALID
+                && self::getType($coid)!=self::COID_ROOT) {
+            $segments = explode('/', $coid->getPath());
+            return $segments[1];
+        } else
+            return null;
+    }
+
+    /**
+     * Get the version segment of a valid, versioned COID or null if not available.
+     *
+     * @param IRI $coid
+     * @return string|null
+     */
+    public static function getVersion(IRI $coid) : ?string {
+        if (self::getType($coid)==self::COID_VERSIONED) {
+            $segments = explode('/', $coid->getPath());
+            return $segments[2];
+        } else
+            return null;
+    }
+
+    /**
+     * Get the version segment of a versioned or version wildcard COID or
+     * null if not available.
+     *
+     * @param IRI $coid
+     * @return string|null
+     */
+    public static function getVersionWildcard(IRI $coid) : ?string {
+        if (self::getType($coid)==self::COID_VERSION_WILDCARD) {
+            $segments = explode('/', $coid->getPath());
+            return $segments[2];
+        } else
+            return null;
+    }
+
+    /**
+     * Returns the COID itself if it is a root COID or a new IRI object
+     * representing the namespace underlying the given COID.
+     *
+     * @param IRI $coid
+     * @return IRI|null
+     */
+    public static function getNamespaceCOID(IRI $coid) : ?IRI {
+        switch (self::getType($coid)) {
+            case self::COID_ROOT:
+                return $coid;
+            case self::COID_UNVERSIONED:
+            case self::COID_VERSIONED:
+            case self::COID_VERSION_WILDCARD:
+                return new IRI('coid://'.$coid->getHost());
+            default:
+                return null;
+        }
     }
-  }
 
 }