Help With City Commemorative Attribution

I think a follis is AE2 and a reduced follis is AE3

Commemoratives of this type and the Urbs Roma with wolf type were issued as part of the same issue as the GLORIA EXERCITVS coins showing the two soldiers with two or one standard between them. When the weight of the coins was reduced, the standards dropped from two to one but no change was made in the two commemrtives other than they got smaller. Usually the two standards coins are called AE3 while the one standard version is on the border of being too small to be AE3 so some call it AE3/4. To tell which issue produced your coin you need either a weight or to compare it to the two soldiers coins you have and see if it looks more like the big two standards group or the smaller one standard one. It is hard to give an exact cut off between the two since mints varied but this difference becomes obvious if you have a handful of the coins and can see how they fall into two groups. Weights can be deceptive if the coin is corroded or chipped and it is hard to do anything from a photo. Often the small coins are under 2g. while the larger are over but a corroded big one can weigh under that figure so I warn against taking any rule as absolute. Considering this is 18mm, I suspect it (allowing for corrosion) weighs 2g. and would therefore be a 64.

RIC letter coded the portrait busts and published a key to them in the book. Letters were major differences while the numbers were fine points like the type of decorations on the diadem. If the bust faced left they would add an 'l' to the end even if that type only came facing left. A letter like N tells us that this is a specialty bust type not like the common heads and busts that got A or B series designations. If you use the system enough you start to recognize frequently used things like B4 and B5 but I, for one, keep a bookmark in the page where the code is listed so I can find it easily. I don't know if online RIC clones bother explaining this or not but they should if they are going to call a bust by its letter code.

IMHO the reason to use Helvetica's site is to see photos of her coins to confirm what you may feel might be ID matches to RIC or her lists made from RIC. If the numbers are really important to you, you need to bite the bullet and buy the volumes of RIC that cover the coins you collect.

Thanks everyone for the help. And thanks doug for the great info. So much more to the sizes of these commemoratives than I thought!