The General classification of shipyards. Any yard can repair a ship one class higher than it can build.
In general it takes a given population and industrial base to support a shipyard. The bigger the shipyard, the more people it takes. (I'm still thinking about numbers). Truly huge populations in the billions can support multiple shipyards. The Sol system for example has five class A shipyards, 10 class B shipyards, and nearly any station in orbit is at least a class D.
As a general rule a system or planet will have twice as many of the next lowest class ship yard as they do their best shipyard. So if they have a single class B they will have two class C and four class D.
The class of a shipyard is not an indication of how many ships it can build at a time. A single class A ship yard can have dozens of ships in the ways. It is not a case of one ship to the yard at a time. The numbers will be a reflection of need and manpower available. All the tech in the universe will not overcome the manpower issue. Starships, like the largest ships on modern Earth are hand built objects.
This is not to say that automation is not used. Per example any Ane ship yard will be hip deep in bios and berks. Vicharrian yards supplement the admittedly not large population with robots.
Class A[]
Build anything. These yards have the capacity to built the biggest and highest tech ships.
Class B[]
Build up to the 400 meter range. The technology and drives are the best but they don't have the resources for things like Federation heavy Cruisers, or massive bulk haulers. They also tend to be limited in the number of ships they can build at once.
Class C[]
Small ship building. Under 150 meter range. This yard could build a defiant for example. Large cutters small frigates and free traders. They don't tend to be up on the latest methods or technology. Usually less than ten ships at a time.
Class D[]
Repair facilities without the ability to build ships of any size.