function validateCity1(executionContext) {
var formContext = typeof executionContext != 'undefined' ? executionContext.getFormContext() : Xrm.Page; // get formContext
var pattern = /[^a-z]/ig;
var fieldName = 'address1_city';
var currentValue = formContext.getAttribute(fieldName).getValue();
if (pattern.test(currentValue)) {
formContext.getControl(fieldName).setNotification('Invalid value, please enter only letters.');
} else {
formContext.getControl(fieldName).clearNotification();
}
}