Here is the way I use to remember how to do the cardinalities for associative entities:
1) Picture/draw the ER diagram Many-to-Many relationship between the two entity types (without the associative entity).
2) Add the box for the associative entity inbetween them.
3) Move each of the two cardinalities that are next to the two entity type boxes so they are on the opposite sides of the associative enitity box (in other words, next to the associative entity box but on the other side of it).
4) Put 1:1 cardinality next to the boxes for both entity types
You can tell that this is right because the crows feet that represent each side of the Many-to-Many relationship are facing towards the same enitity type (as if the associative entity wasn't there).
This really only maters when the two minimums are different (i.e. one is 1:M and the ohter is 0:M).
P.S. Bud, this is a post that got overwritten a week or two ago when I tried to make a new post right after saving it.
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