The phrase "primary categories" is correct and usable in written English.
You can use it when you want to refer to a group of types of things that can be divided broadly into further subgroups. For example, "For this project, I'll need to break down the data into three primary categories: age, gender, and location."
There are really three primary categories: 1. Purpuric mycosis fungoides.
Two primary categories were identified, as well five dimensions in each element and characteristic categories.
First, mass, energy, and property integration are described as the three primary categories of process integration.
The primary categories of risk in this phase relate to the project site and construction.
Texture alone has five primary categories (tender, crunchy, crisp, smooth, soft).
Probabilistic methods have been successfully applied taking into account two primary categories of uncertainties: natural variabilities and modeling uncertainties.
We have not yet fully achieved a total system of upward communications designed to tap the various primary categories of communications needs.
In most years, there is a throng of outfield candidates for the All-Star team, but this season many of the league leaders in the primary categories are infielders.
External entrepreneurs consider money, time, opportunity cost, etc. as the primary categories for consideration alongside the intensity of their desire in determining whether or not to take the first step.
When we met again with Vida Verde on Friday, 2/26 to discuss project ideas that would address co-op needs, we discovered that all of our ideas fell into three primary categories: Coordination, Product Sales, and Marketing.
In the absence of the alternatives provided for in Section A.2.d, the expenses included in this category must be allocated first on the basis of primary categories of users, including students, professional employees, and other users.
