There is a need to create "abstract" element templates in AF, and this has been requested several times.
2012: https://pisquare.osisoft.com/message/4172
2014: https://pisquare.osisoft.com/message/27621#comment-27621
2017: https://pisquare.osisoft.com/thread/32721-possible-to-define-a-virtual-element-template
An abstract class/template is one that you must create a derived version of yourself, you cannot use it directly. It's a base template, but you want to prevent users from instantiating it directly.
You might implement the general attributes for pumps as an abstract template, but you require users to create a derived template for each pump type they have, and then instantiate an element from that.
ADMIN RESPONSE
Aug 19, 2022
In AF 2018 SP2, you can designate a template to be "base template only".
I've worked on a number of projects where this functionality would be useful - having a base template to define all the common attributes of an asset class, but where there is a specific requirement (usually a business rule) to only instantiate elements based on derived templates in the element hierarchy.
As a AF designer i would like to create a set of base templates which contain some core functionality. From these base templates, the actual templates that i use to create the elements are derived. I do not want users to be able to create an instance of these base templates. Preferrable, there is a visual difference in PSE to show these are abstract. Currently i prefix these with two underscores.
