Shape.NameID Property (Visio)
Returns a unique name for a shape. Read-only.
The NameID property returns a unique identifier for each shape on a page or master. The identifier has the following form: sheet.N, where N is the shape's ID property. The value of the NameID property is unique within a page or master, but not across pages or masters. At any moment, no other shape on the same page or master has the same NameID property. However, shapes on other pages or masters may have the same NameID property.
The value of a shape's UniqueID property is unique across pages and masters.
Also, NameID properties are reused. If a shape whose NameID property is sheet.N is deleted, a shape subsequently added to the same context may be assigned sheet.N as its NameID property. Therefore, persisting NameID properties in separate data stores is generally not as sound as persisting UniqueID properties.