The source code

    /*!
     * Ext JS Library 3.2.1
     * Copyright(c) 2006-2010 Ext JS, Inc.
     * licensing@extjs.com
     * http://www.extjs.com/license
     */
    /**
     * @class Ext.data.Types
     * This is s static class containing the system-supplied data types which may be given to a {@link Ext.data.Field Field}.
     * The properties in this class are used as type indicators in the {@link Ext.data.Field Field} class, so to
     * test whether a Field is of a certain type, compare the {@link Ext.data.Field#type type} property against properties
     * of this class.
     * Developers may add their own application-specific data types to this class. Definition names must be UPPERCASE.
     * each type definition must contain three properties:
     *
     * convert : FunctionA function to convert raw data values from a data block into the data
     * to be stored in the Field. The function is passed the collowing parameters:
     *
     * v : MixedThe data value as read by the Reader, if undefined will use
     * the configured {@link Ext.data.Field#defaultValue defaultValue}.
     * rec : MixedThe data object containing the row as read by the Reader.
     * Depending on the Reader type, this could be an Array ({@link Ext.data.ArrayReader ArrayReader}), an object
     * ({@link Ext.data.JsonReader JsonReader}), or an XML element ({@link Ext.data.XMLReader XMLReader}).
     *
     * sortType : Function A function to convert the stored data into comparable form, as defined by {@link Ext.data.SortTypes}.
     * type : String A textual data type name.
     *
     * For example, to create a VELatLong field (See the Microsoft Bing Mapping API) containing the latitude/longitude value of a datapoint on a map from a JsonReader data block
     * which contained the properties lat and long, you would define a new data type like this:
     *
    // Add a new Field data type which stores a VELatLong object in the Record.
    Ext.data.Types.VELATLONG = {
        convert: function(v, data) {
            return new VELatLong(data.lat, data.long);
        },
        sortType: function(v) {
            return v.Latitude;  // When sorting, order by latitude
        },
        type: 'VELatLong'
    };

     * Then, when declaring a Record, use
    var types = Ext.data.Types; // allow shorthand type access
    UnitRecord = Ext.data.Record.create([
        { name: 'unitName', mapping: 'UnitName' },
        { name: 'curSpeed', mapping: 'CurSpeed', type: types.INT },
        { name: 'latitude', mapping: 'lat', type: types.FLOAT },
        { name: 'latitude', mapping: 'lat', type: types.FLOAT },
        { name: 'position', type: types.VELATLONG }
    ]);

     * @singleton
     */
    Ext.data.Types = new function(){
        var st = Ext.data.SortTypes;
        Ext.apply(this, {
            /**
             * @type Regexp
             * @property stripRe
             * A regular expression for stripping non-numeric characters from a numeric value. Defaults to /[\$,%]/g.
             * This should be overridden for localization.
             */
            stripRe: /[\$,%]/g,

            /**
             * @type Object.
             * @property AUTO
             * This data type means that no conversion is applied to the raw data before it is placed into a Record.
             */
            AUTO: {
                convert: function(v){ return v; },
                sortType: st.none,
                type: 'auto'
            },

            /**
             * @type Object.
             * @property STRING
             * This data type means that the raw data is converted into a String before it is placed into a Record.
             */
            STRING: {
                convert: function(v){ return (v === undefined || v === null) ? '' : String(v); },
                sortType: st.asUCString,
                type: 'string'
            },

            /**
             * @type Object.
             * @property INT
             * This data type means that the raw data is converted into an integer before it is placed into a Record.
             * The synonym INTEGER is equivalent.
             */
            INT: {
                convert: function(v){
                    return v !== undefined && v !== null && v !== '' ?
                        parseInt(String(v).replace(Ext.data.Types.stripRe, ''), 10) : 0;
                },
                sortType: st.none,
                type: 'int'
            },

            /**
             * @type Object.
             * @property FLOAT
             * This data type means that the raw data is converted into a number before it is placed into a Record.
             * The synonym NUMBER is equivalent.
             */
            FLOAT: {
                convert: function(v){
                    return v !== undefined && v !== null && v !== '' ?
                        parseFloat(String(v).replace(Ext.data.Types.stripRe, ''), 10) : 0;
                },
                sortType: st.none,
                type: 'float'
            },

            /**
             * @type Object.
             * @property BOOL
             * This data type means that the raw data is converted into a boolean before it is placed into
             * a Record. The string "true" and the number 1 are converted to boolean true.
             * The synonym BOOLEAN is equivalent.
             */
            BOOL: {
                convert: function(v){ return v === true || v === 'true' || v == 1; },
                sortType: st.none,
                type: 'bool'
            },

            /**
             * @type Object.
             * @property DATE
             * This data type means that the raw data is converted into a Date before it is placed into a Record.
             * The date format is specified in the constructor of the {@link Ext.data.Field} to which this type is
             * being applied.
             */
            DATE: {
                convert: function(v){
                    var df = this.dateFormat;
                    if(!v){
                        return null;
                    }
                    if(Ext.isDate(v)){
                        return v;
                    }
                    if(df){
                        if(df == 'timestamp'){
                            return new Date(v*1000);
                        }
                        if(df == 'time'){
                            return new Date(parseInt(v, 10));
                        }
                        return Date.parseDate(v, df);
                    }
                    var parsed = Date.parse(v);
                    return parsed ? new Date(parsed) : null;
                },
                sortType: st.asDate,
                type: 'date'
            }
        });

        Ext.apply(this, {
            /**
             * @type Object.
             * @property BOOLEAN
             * This data type means that the raw data is converted into a boolean before it is placed into
             * a Record. The string "true" and the number 1 are converted to boolean true.
             * The synonym BOOL is equivalent.
             */
            BOOLEAN: this.BOOL,
            /**
             * @type Object.
             * @property INTEGER
             * This data type means that the raw data is converted into an integer before it is placed into a Record.
             * The synonym INT is equivalent.
             */
            INTEGER: this.INT,
            /**
             * @type Object.
             * @property NUMBER
             * This data type means that the raw data is converted into a number before it is placed into a Record.
             * The synonym FLOAT is equivalent.
             */
            NUMBER: this.FLOAT
        });
    };