A dialog function requires an identifier for each dialog box control that it acts on. The dialog function uses string identifiers.
String identifiers are the same as the identifiers used in the dialog record. For example:
CheckBox 8, 56, 203, 16, "Check to display controls",. Chk1
The controls identifier and label are different. An identifier begins with a period and is the last parameter in a dialog
box control instruction. In the sample code above Check to display controls is the label and Chk1 is the identifier.