diff --git a/MangoPay/Address.php b/MangoPay/Address.php
index 59eba588..5595804a 100644
--- a/MangoPay/Address.php
+++ b/MangoPay/Address.php
@@ -40,6 +40,7 @@ class Address extends Libraries\Dto
     /**
      * Country.
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $Country;
 
diff --git a/MangoPay/BankAccountDetailsOTHER.php b/MangoPay/BankAccountDetailsOTHER.php
index a14042e0..efad54f2 100644
--- a/MangoPay/BankAccountDetailsOTHER.php
+++ b/MangoPay/BankAccountDetailsOTHER.php
@@ -17,6 +17,7 @@ class BankAccountDetailsOTHER extends Libraries\Dto implements BankAccountDetail
      * The Country associate to the BankAccount,
      * ISO 3166-1 alpha-2 format is expected
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $Country;
 
diff --git a/MangoPay/BankingAliasIBAN.php b/MangoPay/BankingAliasIBAN.php
index ab0c4f8d..c01ca5d8 100644
--- a/MangoPay/BankingAliasIBAN.php
+++ b/MangoPay/BankingAliasIBAN.php
@@ -28,6 +28,7 @@ class BankingAliasIBAN extends BankingAlias
     /**
      * The country
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $Country;
 }
diff --git a/MangoPay/BankingAliasOTHER.php b/MangoPay/BankingAliasOTHER.php
index a308ddd8..81b3933c 100644
--- a/MangoPay/BankingAliasOTHER.php
+++ b/MangoPay/BankingAliasOTHER.php
@@ -21,6 +21,7 @@ class BankingAliasOTHER extends BankingAlias
 
     /**
      * Country
+     * @see \MangoPay\CountryIso
      */
     public $Country;
 }
diff --git a/MangoPay/Card.php b/MangoPay/Card.php
index a396c814..d84a0bac 100644
--- a/MangoPay/Card.php
+++ b/MangoPay/Card.php
@@ -34,6 +34,7 @@ class Card extends Libraries\EntityBase
     /**
      * Card type
      * @var string
+     * @see \MangoPay\CardType
      */
     public $CardType;
 
@@ -52,6 +53,7 @@ class Card extends Libraries\EntityBase
     /**
      * Country
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $Country;
 
diff --git a/MangoPay/CardPreAuthorization.php b/MangoPay/CardPreAuthorization.php
index 2b640438..faec998d 100644
--- a/MangoPay/CardPreAuthorization.php
+++ b/MangoPay/CardPreAuthorization.php
@@ -163,12 +163,14 @@ class CardPreAuthorization extends Libraries\EntityBase
     /**
      * Requested3DSVersion
      * @var string
+     * @see \MangoPay\Supported3DSVersion
      */
     public $Requested3DSVersion;
 
     /**
      * Applied3DSVersion
      * @var string
+     * @see \MangoPay\Supported3DSVersion
      */
     public $Applied3DSVersion;
 
diff --git a/MangoPay/CardRegistration.php b/MangoPay/CardRegistration.php
index b9e10f38..05312412 100644
--- a/MangoPay/CardRegistration.php
+++ b/MangoPay/CardRegistration.php
@@ -16,6 +16,7 @@ class CardRegistration extends Libraries\EntityBase
     /**
      * CardType
      * @var string
+     * @see \MangoPay\CardType
      */
     public $CardType;
 
diff --git a/MangoPay/CardType.php b/MangoPay/CardType.php
new file mode 100644
index 00000000..3dbc3662
--- /dev/null
+++ b/MangoPay/CardType.php
@@ -0,0 +1,16 @@
+<?php
+
+namespace MangoPay;
+
+class CardType
+{
+    const CbVisaMastercard = 'CB_VISA_MASTERCARD';
+    const Amex = 'AMEX';
+    const Diners = 'DINERS';
+    const Masterpass = 'MASTERPASS';
+    const Maestro = 'MAESTRO';
+    const P24 = 'P24';
+    const Ideal = 'IDEAL';
+    const Bcmc = 'BCMC';
+    const Paylib = 'PAYLIB';
+}
diff --git a/MangoPay/CountryAuthorization.php b/MangoPay/CountryAuthorization.php
index 83a808c1..c62cbc2b 100644
--- a/MangoPay/CountryAuthorization.php
+++ b/MangoPay/CountryAuthorization.php
@@ -10,6 +10,7 @@ class CountryAuthorization extends Libraries\EntityBase
     /**
      * The code of the country in the ISO 3166-1 alpha-2 format.
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $CountryCode;
 
diff --git a/MangoPay/CountryIso.php b/MangoPay/CountryIso.php
new file mode 100644
index 00000000..7916f12f
--- /dev/null
+++ b/MangoPay/CountryIso.php
@@ -0,0 +1,259 @@
+<?php
+
+namespace MangoPay;
+
+/**
+ * Countries, in valid ISO 3166-1 alpha-2 format
+ */
+class CountryIso
+{
+    const AD = 'AD';
+    const AE = 'AE';
+    const AF = 'AF';
+    const AG = 'AG';
+    const AI = 'AI';
+    const AL = 'AL';
+    const AM = 'AM';
+    const AO = 'AO';
+    const AQ = 'AQ';
+    const AR = 'AR';
+    const AS = 'AS';
+    const AT = 'AT';
+    const AU = 'AU';
+    const AW = 'AW';
+    const AX = 'AX';
+    const AZ = 'AZ';
+    const BA = 'BA';
+    const BB = 'BB';
+    const BD = 'BD';
+    const BE = 'BE';
+    const BF = 'BF';
+    const BG = 'BG';
+    const BH = 'BH';
+    const BI = 'BI';
+    const BJ = 'BJ';
+    const BL = 'BL';
+    const BM = 'BM';
+    const BN = 'BN';
+    const BO = 'BO';
+    const BQ = 'BQ';
+    const BR = 'BR';
+    const BS = 'BS';
+    const BT = 'BT';
+    const BV = 'BV';
+    const BW = 'BW';
+    const BY = 'BY';
+    const BZ = 'BZ';
+    const CA = 'CA';
+    const CC = 'CC';
+    const CD = 'CD';
+    const CF = 'CF';
+    const CG = 'CG';
+    const CH = 'CH';
+    const CI = 'CI';
+    const CK = 'CK';
+    const CL = 'CL';
+    const CM = 'CM';
+    const CN = 'CN';
+    const CO = 'CO';
+    const CR = 'CR';
+    const CU = 'CU';
+    const CV = 'CV';
+    const CW = 'CW';
+    const CX = 'CX';
+    const CY = 'CY';
+    const CZ = 'CZ';
+    const DE = 'DE';
+    const DJ = 'DJ';
+    const DK = 'DK';
+    const DM = 'DM';
+    const DO = 'DO';
+    const DZ = 'DZ';
+    const EC = 'EC';
+    const EE = 'EE';
+    const EG = 'EG';
+    const EH = 'EH';
+    const ER = 'ER';
+    const ES = 'ES';
+    const ET = 'ET';
+    const FI = 'FI';
+    const FJ = 'FJ';
+    const FK = 'FK';
+    const FM = 'FM';
+    const FO = 'FO';
+    const FR = 'FR';
+    const GA = 'GA';
+    const GB = 'GB';
+    const GD = 'GD';
+    const GE = 'GE';
+    const GF = 'GF';
+    const GG = 'GG';
+    const GH = 'GH';
+    const GI = 'GI';
+    const GL = 'GL';
+    const GM = 'GM';
+    const GN = 'GN';
+    const GP = 'GP';
+    const GQ = 'GQ';
+    const GR = 'GR';
+    const GS = 'GS';
+    const GT = 'GT';
+    const GU = 'GU';
+    const GW = 'GW';
+    const GY = 'GY';
+    const HK = 'HK';
+    const HM = 'HM';
+    const HN = 'HN';
+    const HR = 'HR';
+    const HT = 'HT';
+    const HU = 'HU';
+    const ID = 'ID';
+    const IE = 'IE';
+    const IL = 'IL';
+    const IM = 'IM';
+    const IN = 'IN';
+    const IO = 'IO';
+    const IQ = 'IQ';
+    const IR = 'IR';
+    const IS = 'IS';
+    const IT = 'IT';
+    const JE = 'JE';
+    const JM = 'JM';
+    const JO = 'JO';
+    const JP = 'JP';
+    const KE = 'KE';
+    const KG = 'KG';
+    const KH = 'KH';
+    const KI = 'KI';
+    const KM = 'KM';
+    const KN = 'KN';
+    const KP = 'KP';
+    const KR = 'KR';
+    const KW = 'KW';
+    const KY = 'KY';
+    const KZ = 'KZ';
+    const LA = 'LA';
+    const LB = 'LB';
+    const LC = 'LC';
+    const LI = 'LI';
+    const LK = 'LK';
+    const LR = 'LR';
+    const LS = 'LS';
+    const LT = 'LT';
+    const LU = 'LU';
+    const LV = 'LV';
+    const LY = 'LY';
+    const MA = 'MA';
+    const MC = 'MC';
+    const MD = 'MD';
+    const ME = 'ME';
+    const MF = 'MF';
+    const MG = 'MG';
+    const MH = 'MH';
+    const MK = 'MK';
+    const ML = 'ML';
+    const MM = 'MM';
+    const MN = 'MN';
+    const MO = 'MO';
+    const MP = 'MP';
+    const MQ = 'MQ';
+    const MR = 'MR';
+    const MS = 'MS';
+    const MT = 'MT';
+    const MU = 'MU';
+    const MV = 'MV';
+    const MW = 'MW';
+    const MX = 'MX';
+    const MY = 'MY';
+    const MZ = 'MZ';
+    const NA = 'NA';
+    const NC = 'NC';
+    const NE = 'NE';
+    const NF = 'NF';
+    const NG = 'NG';
+    const NI = 'NI';
+    const NL = 'NL';
+    const NO = 'NO';
+    const NP = 'NP';
+    const NR = 'NR';
+    const NU = 'NU';
+    const NZ = 'NZ';
+    const OM = 'OM';
+    const PA = 'PA';
+    const PE = 'PE';
+    const PF = 'PF';
+    const PG = 'PG';
+    const PH = 'PH';
+    const PK = 'PK';
+    const PL = 'PL';
+    const PM = 'PM';
+    const PN = 'PN';
+    const PR = 'PR';
+    const PS = 'PS';
+    const PT = 'PT';
+    const PW = 'PW';
+    const PY = 'PY';
+    const QA = 'QA';
+    const RE = 'RE';
+    const RO = 'RO';
+    const RS = 'RS';
+    const RU = 'RU';
+    const RW = 'RW';
+    const SA = 'SA';
+    const SB = 'SB';
+    const SC = 'SC';
+    const SD = 'SD';
+    const SE = 'SE';
+    const SG = 'SG';
+    const SH = 'SH';
+    const SI = 'SI';
+    const SJ = 'SJ';
+    const SK = 'SK';
+    const SL = 'SL';
+    const SM = 'SM';
+    const SN = 'SN';
+    const SO = 'SO';
+    const SR = 'SR';
+    const SS = 'SS';
+    const ST = 'ST';
+    const SV = 'SV';
+    const SX = 'SX';
+    const SY = 'SY';
+    const SZ = 'SZ';
+    const TC = 'TC';
+    const TD = 'TD';
+    const TF = 'TF';
+    const TG = 'TG';
+    const TH = 'TH';
+    const TJ = 'TJ';
+    const TK = 'TK';
+    const TL = 'TL';
+    const TM = 'TM';
+    const TN = 'TN';
+    const TO = 'TO';
+    const TR = 'TR';
+    const TT = 'TT';
+    const TV = 'TV';
+    const TW = 'TW';
+    const TZ = 'TZ';
+    const UA = 'UA';
+    const UG = 'UG';
+    const UM = 'UM';
+    const US = 'US';
+    const UY = 'UY';
+    const UZ = 'UZ';
+    const VA = 'VA';
+    const VC = 'VC';
+    const VE = 'VE';
+    const VG = 'VG';
+    const VI = 'VI';
+    const VN = 'VN';
+    const VU = 'VU';
+    const WF = 'WF';
+    const WS = 'WS';
+    const YE = 'YE';
+    const YT = 'YT';
+    const ZA = 'ZA';
+    const ZM = 'ZM';
+    const ZW = 'ZW';
+}
diff --git a/MangoPay/Mandate.php b/MangoPay/Mandate.php
index 617ab3c6..4696a998 100644
--- a/MangoPay/Mandate.php
+++ b/MangoPay/Mandate.php
@@ -14,9 +14,10 @@ class Mandate extends Libraries\EntityBase
     public $BankAccountId;
 
     /**
-     * The type of mandate – it will be « SEPA » or « BACS »
-     * but will only be completed once the mandate has been submitted
+     * The type of mandate
+     * It will only be completed once the mandate has been submitted
      * @var string
+     * @see \MangoPay\MandateScheme
      */
     public $Scheme;
 
diff --git a/MangoPay/MandateScheme.php b/MangoPay/MandateScheme.php
new file mode 100644
index 00000000..d0e504c1
--- /dev/null
+++ b/MangoPay/MandateScheme.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace MangoPay;
+
+/**
+ * The type of mandate
+ */
+class MandateScheme
+{
+    const Sepa = "SEPA";
+    const Bacs = "BACS";
+}
diff --git a/MangoPay/PayIn.php b/MangoPay/PayIn.php
index 0042caa9..a2b2e714 100644
--- a/MangoPay/PayIn.php
+++ b/MangoPay/PayIn.php
@@ -26,8 +26,9 @@ class PayIn extends Transaction
     public $PaymentDetails;
 
     /**
-     * ExecutionType { WEB, TOKEN, DIRECT, PREAUTHORIZED, RECURRING_ORDER_EXECUTION }
+     * ExecutionType
      * @var string
+     * @see \MangoPay\PayInExecutionType
      */
     public $ExecutionType;
 
diff --git a/MangoPay/PayInExecutionDetailsDirect.php b/MangoPay/PayInExecutionDetailsDirect.php
index 9750df76..65ac5d68 100644
--- a/MangoPay/PayInExecutionDetailsDirect.php
+++ b/MangoPay/PayInExecutionDetailsDirect.php
@@ -8,8 +8,9 @@
 class PayInExecutionDetailsDirect extends Libraries\Dto implements PayInExecutionDetails
 {
     /**
-     * SecureMode { DEFAULT, FORCE, NO_CHOICE }
+     * SecureMode
      * @var string
+     * @see \MangoPay\PayInExecutionSecureMode
      */
     public $SecureMode;
 
@@ -52,12 +53,14 @@ class PayInExecutionDetailsDirect extends Libraries\Dto implements PayInExecutio
     /**
      * Requested3DSVersion
      * @var string
+     * @see \MangoPay\Supported3DSVersion
      */
     public $Requested3DSVersion;
 
     /**
      * Applied3DSVersion
      * @var string
+     * @see \MangoPay\Supported3DSVersion
      */
     public $Applied3DSVersion;
 
diff --git a/MangoPay/PayInExecutionSecureMode.php b/MangoPay/PayInExecutionSecureMode.php
new file mode 100644
index 00000000..347dc2e5
--- /dev/null
+++ b/MangoPay/PayInExecutionSecureMode.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace MangoPay;
+
+/**
+ * PayIn secure mode, taking into account 3DS2
+ */
+class PayInExecutionSecureMode
+{
+    const Default = 'DEFAULT';
+    const Force = 'FORCE';
+    const NoChoice = 'NO_CHOICE';
+}
diff --git a/MangoPay/PayInExecutionType.php b/MangoPay/PayInExecutionType.php
index 32b38765..859a05cf 100644
--- a/MangoPay/PayInExecutionType.php
+++ b/MangoPay/PayInExecutionType.php
@@ -10,4 +10,7 @@ class PayInExecutionType
     const Direct = 'DIRECT';
     const Web = 'WEB';
     const ExternalInstruction = 'EXTERNAL_INSTRUCTION';
+    const Token = 'TOKEN';
+    const Preauthorized = 'PREAUTHORIZED';
+    const RecurringOrderExecution = 'RECURRING_ORDER_EXECUTION';
 }
diff --git a/MangoPay/PayInPaymentDetailsCard.php b/MangoPay/PayInPaymentDetailsCard.php
index 853c0134..bc1b1275 100644
--- a/MangoPay/PayInPaymentDetailsCard.php
+++ b/MangoPay/PayInPaymentDetailsCard.php
@@ -8,8 +8,9 @@
 class PayInPaymentDetailsCard extends Libraries\Dto implements PayInPaymentDetails
 {
     /**
-     * CardType { CB_VISA_MASTERCARD, AMEX }
+     * CardType
      * @var string
+     * @see \MangoPay\CardType
      */
     public $CardType;
 
diff --git a/MangoPay/PayInWebExtendedView.php b/MangoPay/PayInWebExtendedView.php
index 699ee032..038bf100 100644
--- a/MangoPay/PayInWebExtendedView.php
+++ b/MangoPay/PayInWebExtendedView.php
@@ -20,8 +20,9 @@ class PayInWebExtendedView extends Libraries\Dto
     public $PaymentType;
 
     /**
-     * ExecutionType { WEB, TOKEN, DIRECT, PREAUTHORIZED, RECURRING_ORDER_EXECUTION }
+     * ExecutionType
      * @var string
+     * @see \MangoPay\PayInExecutionType
      */
     public $ExecutionType;
 
diff --git a/MangoPay/Supported3DSVersion.php b/MangoPay/Supported3DSVersion.php
new file mode 100644
index 00000000..382f8cac
--- /dev/null
+++ b/MangoPay/Supported3DSVersion.php
@@ -0,0 +1,13 @@
+<?php
+
+namespace MangoPay;
+
+/**
+ * Supported versions of 3D Secure.
+ * Requesting a specific version is for testing purposes only. Production environments need to use the 3DS2 flow.
+ */
+class Supported3DSVersion
+{
+    const V1 = 'V1';
+    const V2_1 = 'V2_1';
+}
diff --git a/MangoPay/Ubo.php b/MangoPay/Ubo.php
index 8b83ffba..2f85d5f4 100644
--- a/MangoPay/Ubo.php
+++ b/MangoPay/Ubo.php
@@ -21,6 +21,7 @@ class Ubo extends Libraries\EntityBase
 
     /**
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $Nationality;
 
diff --git a/MangoPay/User.php b/MangoPay/User.php
index f5253712..0ea7e7dd 100644
--- a/MangoPay/User.php
+++ b/MangoPay/User.php
@@ -40,6 +40,7 @@ abstract class User extends Libraries\EntityBase
     /**
      * Category of user
      * @var string
+     * @see \MangoPay\UserCategory
      */
     public $UserCategory;
 
diff --git a/MangoPay/UserCategory.php b/MangoPay/UserCategory.php
new file mode 100644
index 00000000..9d2ffdb7
--- /dev/null
+++ b/MangoPay/UserCategory.php
@@ -0,0 +1,12 @@
+<?php
+
+namespace MangoPay;
+
+/**
+ * Depending of the category, users can perform a variety of possible actions.
+ */
+class UserCategory
+{
+    const Owner = 'OWNER';
+    const Payer = 'PAYER';
+}
diff --git a/MangoPay/UserLegal.php b/MangoPay/UserLegal.php
index 5bea326d..9518b12a 100644
--- a/MangoPay/UserLegal.php
+++ b/MangoPay/UserLegal.php
@@ -56,14 +56,14 @@ class UserLegal extends User
     public $LegalRepresentativeBirthday;
 
     /**
-     *
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $LegalRepresentativeNationality;
 
     /**
-     *
      * @var string
+     * @see \MangoPay\CountryIso
      */
     public $LegalRepresentativeCountryOfResidence;
 
diff --git a/MangoPay/UserNatural.php b/MangoPay/UserNatural.php
index c109a8ab..dfd9d900 100644
--- a/MangoPay/UserNatural.php
+++ b/MangoPay/UserNatural.php
@@ -34,12 +34,14 @@ class UserNatural extends User
     /**
     * User's country
     * @var string
+    * @see \MangoPay\CountryIso
     */
     public $Nationality;
 
     /**
     * Country of residence
     * @var string
+    * @see \MangoPay\CountryIso
     */
     public $CountryOfResidence;