The Category and SubCategory for the Performance is inherited from the first PART, Part 1.
From Performance Home
Press [PART SELECT 1]
Press [EDIT]
Touch “Part Settings” > “General”
The Part Main Category and Part SubCategory of Part 1 is applied to the entire Performance.

When you use the Category Search Function (there are three different types of searches concerning instrument programs), you can search for individual Single programs, you can search for a linked set of programs (Multi), you can even search for individual single programs from within a multi program. In order to facilitate searches where a group of single Parts have been linked into a multiple Part program, it makes perfect sense for the first Part to act as the identifier for the group.

Take “CFX CONCERT” — a four Part, 18-Element rendering of an acoustic piano. Each Part separately is not playable alone... each covers a specific set of note ranges and/or velocity ranges... they only make sense as a group. Part 1 acts as the ‘captain’ of this group... so that when you want to recall the entire group, you just have to search for the Part with the identifier for the group (that’s Part 1).

Yes, you can recall just one Part from any group... but the point is you are given both options. When you want to recall the entire group as an entity, you can. And when you want to go into a Multi Part Performance and ‘get’ just one Part, you can, as well.

Example, “Seattle Sections” is a 7-Part Performance. You may want to just grab Part 7, which is a solo cello in the low end and a viola in the middle with a solo violin on top. You may want to use just Part along with a choir sound. You can set the Part Category Search to go and ‘get’ just a specific Part from with a Multi Part Performance.

CATEGORY SEARCHES...
At first the three different types searches are not recognized. It is important to recognize the different types:
_ Performance Category Search — replaces the entire current Performance with another
_ Performance Merge — this Search only happens when you have touched a “+” to Add a new Part (or Parts) to the current Performance
_ Part Category Search — this Search only happens when you are replacing an existing Part; Select the Part then use [SHIFT] + [CATEGORY SEARCH]

Each has a different use and slightly different options available.
Hope that helps.

Thanks.