GUIDFromString Method
The GUIDFromString function converts a string to a GUID, which is an array of type Byte. Variant.
expression.GUIDFromString(String)
expression Required. An expression that returns one of the objects in the Applies To list.
String Required Variant. A string expression which evaluates to a GUID in string form.
Remarks
The Microsoft Jet database engine stores GUIDs as arrays of type Byte. However, Microsoft Access can't return Byte data from a control on a form or report. In order to return the value of a GUID from a control, you must convert it to a string. To convert a GUID to a string, use the StringFromGUID function. To convert a string to a GUID, use the GUIDFromString function.