diff --git a/lib/geo.js b/lib/geo.js
index 30d6931d..1dac1abd 100644
--- a/lib/geo.js
+++ b/lib/geo.js
@@ -138,7 +138,14 @@ function GeoPoint(data) {
   assert(data.lat <= 90, 'lat must be <= 90');
   assert(data.lat >= -90, 'lat must be >= -90');
 
+/**
+   * @property {Number} lat The latitude point in degrees. Range: -90 to 90.
+*/
   this.lat = data.lat;
+
+/**
+   * @property {Number} lng The longitude point in degrees. Range: -90 to 90.
+*/  
   this.lng = data.lng;
 }
 
diff --git a/lib/validations.js b/lib/validations.js
index ab2c85ba..200bf6ba 100644
--- a/lib/validations.js
+++ b/lib/validations.js
@@ -11,10 +11,10 @@ exports.Validatable = Validatable;
  * This class provides methods that add validation cababilities to models.
  * Each of this validations run when `obj.isValid()` method called.
  *
- * Each configurator can accept n params (n-1 field names and one config). Config
- * is {Object} depends on specific validation, but all of them has one common part:
- * `message` member. It can be just string, when only one situation possible,
- * e.g. `Post.validatesPresenceOf('title', { message: 'can not be blank' });`
+ * Each configurator can accept *n* params (*n*-1 field names and one config). Config
+ * is {Object} depends on specific validation, but all of them have a
+ * `message` member property. It can be just string, when only one situation possible,
+ * For example: `Post.validatesPresenceOf('title', { message: 'can not be blank' });`
  *
  * In more complicated cases it can be {Hash} of messages (for each case):
  * `User.validatesLengthOf('password', { min: 6, max: 20, message: {min: 'too short', max: 'too long'}});`
@@ -24,24 +24,31 @@ function Validatable() {
 }
 
 /**
- * Validate presence. This validation fails when validated field is blank.
- *
- * Default error message "can't be blank"
+ * Validate presence of one or more specified properties. 
+ * Requires a model to include a property to be considered valid; fails when validated field is blank.
  *
  * For example, validate presence of title
  * ```
  * Post.validatesPresenceOf('title');
  * ```
- *Example with custom message
+ * Validate that model has first, last, and age properties:
+ * ```
+ * User.validatesPresenceOf('first', 'last', 'age');
+ * ```
+ * Example with custom message
  * ```
  * Post.validatesPresenceOf('title', {message: 'Cannot be blank'});
  * ```
  *
+ * @param {String} propertyName  One or more property names.
+ * @options {Object} errMsg Optional custom error message.  Default is "can't be blank"
+ * @property {String} message Error message to use instead of default.
  */
 Validatable.validatesPresenceOf = getConfigurator('presence');
 
 /**
- * Validate length. Three kinds of validations: min, max, is.
+ * Validate length. Require a property length to be within a specified range.
+ * Three kinds of validations: min, max, is.
  *
  * Default error messages:
  *
@@ -61,11 +68,17 @@ Validatable.validatesPresenceOf = getConfigurator('presence');
  * User.validatesLengthOf('password', {min: 7, message: {min: 'too weak'}});
  * User.validatesLengthOf('state', {is: 2, message: {is: 'is not valid state name'}});
  * ```
+ * @param {String} propertyName  Property name to validate.
+ * @options {Object} Options 
+ * @property {Number} is Value that property must equal to validate.
+ * @property {Number} min Value that property must be less than to be valid.
+ * @property {Number} max Value that property must be less than to be valid.
+ * @property {Object} message Optional Object with string properties for custom error message for each validation: is, min, or max
  */
 Validatable.validatesLengthOf = getConfigurator('length');
 
 /**
- * Validate numericality.
+ * Validate numericality.  Requires a value for property to be either an integer or number.
  *
  * Example
  * ```
@@ -73,19 +86,17 @@ Validatable.validatesLengthOf = getConfigurator('length');
  * User.validatesNumericalityOf('age', {int: true, message: { int: '...' }});
  * ```
  *
- * Default error messages:
- *
+ * @param {String} propertyName  Property name to validate.
+ * @options {Object} Options 
+ * @property {Boolean} int If true, then property must be an integer to be valid.
+ * @property {Object} message Optional object with string properties for 'int' for integer validation.  Default error messages:
  * - number: is not a number
  * - int: is not an integer
- *
- * @sync
- * @nocode
- * @see helper/validateNumericality
  */
 Validatable.validatesNumericalityOf = getConfigurator('numericality');
 
 /**
- * Validate inclusion in set
+ * Validate inclusion in set.  Require a value for property to be in the specified array.
  *
  * Example:
  * ```
@@ -95,33 +106,35 @@ Validatable.validatesNumericalityOf = getConfigurator('numericality');
  * });
  * ```
  *
- * Default error message: is not included in the list
- *
- * @sync
- * @nocode
- * @see helper/validateInclusion
+ * @param {String} propertyName  Property name to validate.
+ * @options {Object} Options 
+ * @property {Array} in Array Property must match one of the values in the array to be valid.
+ * @property {String} message Optional error message if property is not valid.   Default error message: "is not included in the list".
  */
 Validatable.validatesInclusionOf = getConfigurator('inclusion');
 
 /**
- * Validate exclusion
+ * Validate exclusion.  Require a property value not be in the specified array.
  *
  * Example: `Company.validatesExclusionOf('domain', {in: ['www', 'admin']});`
  *
- * Default error message: is reserved
- *
- * @nocode
- * @see helper/validateExclusion
+ * @param {String} propertyName  Property name to validate.
+ * @options {Object} Options 
+ * @property {Array} in Array Property must match one of the values in the array to be valid.
+ * @property {String} message Optional error message if property is not valid.  Default error message: "is reserved".
  */
 Validatable.validatesExclusionOf = getConfigurator('exclusion');
 
 /**
- * Validate format
+ * Validate format. Require a model to include a property that matches the given format.
  *
- * Default error message: is invalid
- *
- * @nocode
- * @see helper/validateFormat
+ * Require a model to include a property that matches the given format.  Example:
+ * `User.validatesFormat('name', {with: /\w+/});`
+ * 
+ * @param {String} propertyName  Property name to validate.
+ * @options {Object} Options 
+ * @property {RegExp} with Regular expression to validate format.
+ * @property {String} message Optional error message if property is not valid.  Default error message: " is invalid".
  */
 Validatable.validatesFormatOf = getConfigurator('format');
 
@@ -178,19 +191,32 @@ Validatable.validate = getConfigurator('custom');
 Validatable.validateAsync = getConfigurator('custom', {async: true});
 
 /**
- * Validate uniqueness
+ * Validate uniqueness. Ensure the value for property is unique in the collection of models.
+ * Not available for all connectors. Currently supported with these connectors:
+ *  - In Memory
+ *  - Oracle
+ *  - MongoDB
  *
- * Default error message: is not unique
+ * ```
+ * // The login must be unique across all User instances.
+ * User.validatesUniquenessOf('login');
  *
- * @async
- * @nocode
- * @see helper/validateUniqueness
+ * // Assuming SiteUser.belongsTo(Site)
+ * // The login must be unique within each Site.
+ * SiteUser.validateUniquenessOf('login', { scopedTo: ['siteId'] });
+ * ```
+
+ * @param {String} propertyName  Property name to validate.
+ * @options {Object} Options 
+ * @property {RegExp} with Regular expression to validate format.
+ * @property {Array.<String>} scopedTo List of properties defining the scope.
+ * @property {String} message Optional error message if property is not valid.  Default error message: "is not unique".
  */
 Validatable.validatesUniquenessOf = getConfigurator('uniqueness', {async: true});
 
 // implementation of validators
 
-/**
+/*!
  * Presence validator
  */
 function validatePresence(attr, conf, err) {
@@ -199,7 +225,7 @@ function validatePresence(attr, conf, err) {
   }
 }
 
-/**
+/*!
  * Length validator
  */
 function validateLength(attr, conf, err) {
@@ -217,7 +243,7 @@ function validateLength(attr, conf, err) {
   }
 }
 
-/**
+/*!
  * Numericality validator
  */
 function validateNumericality(attr, conf, err) {
@@ -231,7 +257,7 @@ function validateNumericality(attr, conf, err) {
   }
 }
 
-/**
+/*!
  * Inclusion validator
  */
 function validateInclusion(attr, conf, err) {
@@ -242,7 +268,7 @@ function validateInclusion(attr, conf, err) {
   }
 }
 
-/**
+/*!
  * Exclusion validator
  */
 function validateExclusion(attr, conf, err) {
@@ -253,7 +279,7 @@ function validateExclusion(attr, conf, err) {
   }
 }
 
-/**
+/*!
  * Format validator
  */
 function validateFormat(attr, conf, err) {
@@ -268,19 +294,28 @@ function validateFormat(attr, conf, err) {
   }
 }
 
-/**
+/*!
  * Custom validator
  */
 function validateCustom(attr, conf, err, done) {
   conf.customValidator.call(this, err, done);
 }
 
-/**
+/*!
  * Uniqueness validator
  */
 function validateUniqueness(attr, conf, err, done) {
   var cond = {where: {}};
   cond.where[attr] = this[attr];
+
+  if (conf && conf.scopedTo) {
+    conf.scopedTo.forEach(function(k) {
+      var val = this[k];
+      if (val !== undefined)
+        cond.where[k] = this[k];
+    }, this);
+  }
+
   this.constructor.find(cond, function (error, found) {
     if (error) {
       return err();
@@ -312,16 +347,14 @@ function getConfigurator(name, opts) {
 }
 
 /**
- * This method performs validation, triggers validation hooks.
- * Before validation `obj.errors` collection cleaned.
+ * This method performs validation and triggers validation hooks.
+ * Before validation the `obj.errors` collection is cleaned.
  * Each validation can add errors to `obj.errors` collection.
  * If collection is not blank, validation failed.
  *
- * @warning This method can be called as sync only when no async validation
+ * NOTE: This method can be called as synchronous only when no asynchronous validation is
  * configured. It's strongly recommended to run all validations as asyncronous.
  *
- * Returns true if no async validation configured and all passed
- *
  * Example: ExpressJS controller: render user if valid, show flash otherwise
  * ```
  * user.isValid(function (valid) {
@@ -329,7 +362,21 @@ function getConfigurator(name, opts) {
  *     else res.flash('error', 'User is not valid'), console.log(user.errors), res.redirect('/users');
  * });
  * ```
+ * Another example:
+ * ```
+ * user.isValid(function (valid) {
+ *     if (!valid) {
+ *           console.log(user.errors);
+ *         // => hash of errors
+ *         // => {
+ *         // => username: [errmessage, errmessage, ...],
+ *         // => email: ...
+ *         // => }
+ *     }
+ * });
+ * ```
  * @param {Function} callback called with (valid)
+ * @returns {Boolean} True if no asynchronouse validation is configured and all properties pass validation.
  */
 Validatable.prototype.isValid = function (callback, data) {
   var valid = true, inst = this, wait = 0, async = false;
@@ -521,7 +568,7 @@ function nullCheck(attr, conf, err) {
   return false;
 }
 
-/**
+/*!
  * Return true when v is undefined, blank array, null or empty string
  * otherwise returns false
  *
@@ -586,6 +633,56 @@ function ErrorCodes(messages) {
   });
 }
 
+/**
+ * ValidationError is raised when the application attempts to save an invalid model instance.
+ * Example:
+ * ```
+ * {
+ *   "name": "ValidationError",
+ *   "status": 422,
+ *   "message": "The Model instance is not valid. \
+ *  See `details` property of the error object for more info.",
+ *   "statusCode": 422,
+ *   "details": {
+ *     "context": "user",
+  *    "codes": {
+  *      "password": [
+ *         "presence"
+ *       ],
+ *       "email": [
+ *         "uniqueness"
+ *       ]
+ *    },
+ *     "messages": {
+ *       "password": [
+ *        "can't be blank"
+ *      ],
+ *       "email": [
+ *         "Email already exists"
+ *       ]
+ *     }
+ *   },
+ * }
+ * ```
+ * You might run into situations where you need to raise a validation error yourself, for example in a "before" hook or a
+ * custom model method.
+ * ```
+ * MyModel.prototype.preflight = function(changes, callback) {
+ *   // Update properties, do not save to db
+ *   for (var key in changes) {
+ *     model[key] = changes[key];
+ *   }
+ * 
+ *   if (model.isValid()) {
+ *     return callback(null, { success: true });
+ *   }
+ * 
+ *   // This line shows how to create a ValidationError
+ *   err = new ValidationError(model);
+ *   callback(err);
+ * }
+ * ```
+*/
 function ValidationError(obj) {
   if (!(this instanceof ValidationError)) return new ValidationError(obj);
 
diff --git a/package.json b/package.json
index b03fcd36..a569f21f 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "loopback-datasource-juggler",
-  "version": "1.4.0",
+  "version": "1.5.0",
   "description": "LoopBack DataSoure Juggler",
   "keywords": [
     "StrongLoop",
diff --git a/test/validations.test.js b/test/validations.test.js
index 54a50237..f01414aa 100644
--- a/test/validations.test.js
+++ b/test/validations.test.js
@@ -1,5 +1,6 @@
 // This test written in mocha+should.js
 var should = require('./init.js');
+var async = require('async');
 
 var j = require('../'), db, User;
 var ValidationError = j.ValidationError;
@@ -172,6 +173,41 @@ describe('validations', function () {
       })).should.not.be.ok;
     });
 
+    it('should support multi-key constraint', function(done) {
+      var EMAIL = 'user@xample.com';
+      var SiteUser = db.define('SiteUser', {
+        siteId: String,
+        email: String
+      });
+      SiteUser.validatesUniquenessOf('email', { scopedTo: ['siteId'] });
+      async.waterfall([
+        function automigrate(next) {
+          db.automigrate(next);
+        },
+        function createSite1User(next) {
+          SiteUser.create(
+            { siteId: 1, email: EMAIL },
+            next);
+        },
+        function createSite2User(user1, next) {
+          SiteUser.create(
+            { siteId: 2, email: EMAIL },
+            next);
+        },
+        function validateDuplicateUser(user2, next) {
+          var user3 = new SiteUser({ siteId: 1, email: EMAIL });
+          user3.isValid(function(valid) {
+            valid.should.be.false;
+            next();
+          });
+        }
+      ], function(err) {
+        if (err && err.name == 'ValidationError') {
+          console.error('ValidationError:', err.details.messages);
+        }
+        done(err);
+      });
+    });
   });
 
   describe('format', function () {