using System.ComponentModel;

public class NoteInfo : System.ComponentModel.IDataErrorInfo {

    //... 

    //Stores error descriptions for the Day, Month, Year and NoteID properties 

    Hashtable propertyErrors;

    //Stores an error description for the item 

    string noteError;

    public NoteInfo(int _noteID, int _day, int _month, int _year) {

        //... 

        //Set errors to empty strings 

        propertyErrors = new Hashtable();

        propertyErrors.Add("Day", "");

        propertyErrors.Add("Month", "");

        propertyErrors.Add("Year", "");

        propertyErrors.Add("NoteID", "");

        noteError = "";

    }

    public int NoteID { /*...*/  }

    public int Day { /*...*/  }

    public int Month { /*...*/  }

    public int Year { /*...*/  }

    //Gets and sets an error for the current item 

    internal string NoteError {

        get { return noteError; }

        set {

            if(noteError == value) return;

            noteError = value;

            OnNoteChanged();

        }

    }

    public void ClearErrors() {

        SetColumnError("Day", "");

        SetColumnError("Month", "");

        SetColumnError("Year", "");

        NoteError = "";

    }

    //Sets an error for an item's property 

    public void SetColumnError(string elem, string error) {

        if(propertyErrors.ContainsKey(elem)) {

            if((string)propertyErrors[elem] == error) return;

            propertyErrors[elem] = error;

            OnNoteChanged();

        }

    }

    //Gets an error for an item's property 

    public string GetColumnError(string elem) {

        if(propertyErrors.ContainsKey(elem))

            return (string)propertyErrors[elem];

        else 

            return "";

    }

    //The owner collection 

    internal ProjectNotes Owner { /*...*/  }

    //Notify the owner collection about record changing 

    protected void OnNoteChanged() {           

        if(Owner != null)

            Owner.OnRecordChanged(new  ListChangedEventArgs(ListChangedType.ItemChanged,

              Owner.IndexOf(this)));

    }

    #region IDataErrorInfo Members

    //Returns an error description set for the item's property 

    string IDataErrorInfo.this[string columnName] {

        get {

            return GetColumnError(columnName);

        }

    }

    //Returns an error description set for the current item 

    string IDataErrorInfo.Error {

        get { return noteError; }

    }

    #endregion

}

public class ProjectNotes: CollectionBase, IBindingList {

    //... 

    //Adds a new item to the collection 

    public int Add(NoteInfo nInfo) {

        int index = List.Add(nInfo);           

        return index;

    }

    //Fires the IBindingList.ListChanged event. 

    protected internal void OnRecordChanged(ListChangedEventArgs e) {

        if(ListChanged != null) ListChanged(this, e);

    }

    #region IBindingList Members

    // ... 

    #endregion

}

//Returns the name of the date property containing invalid data 

private string IsValidDate(int day, int month, int year) {

    if(month < 1 || month > 12) return "Month";

    if(day < 1 || day > DateTime.DaysInMonth(year, month)) return "Day";

    if(year < 1980 || year > 2010) return "Year";

    return "";

}

private void ValidateData() {

    ProjectNotes notes = gridControl1.DataSource as ProjectNotes;

    foreach(NoteInfo nInfo in notes) {

        string valid = IsValidDate(nInfo.Day, nInfo.Month, nInfo.Year);

        nInfo.ClearErrors();

        if(valid != "") {

            nInfo.NoteError = "Check the date";

            nInfo.SetColumnError(valid, "Invalid " + valid);

        }   

    }

}