tagOrId in Canvas class

[John Smith]

Can anyone steer me to a reference on "tagOrId" in the canvas class?  It is
a way of referencing objects (i.e. line, arc, circle) on a canvas.  I
understand I can use it to select and manipulate canvas objects.  For
example, you can say, give me all the tags for items with the following
tagOrId, or you can ask for the type of object that has a specific tagOrId.

Does tagOrId stand for "tag or Id" where Id stands for item handle?

Thank you

John Smith