@Asur
https://kenshi.fandom.com/wiki/Using_the_FCS
That wiki page gives you a pretty good primer on how to search specific stuff in Kenshi. In fcs_layout.def, just place those same search strings you used in quotes next to whatever label you want, and it will show up in FCS. For example, you can put in:
Bleedless: RACE "bleed rate == 0"
That will create a new entry called Bleedless in FCS which will list all races that don't bleed.
You can indent each entry, and that will make them show up in subsections in FCS, to help you organize the entries.

Could you help me with Customized fcs def?

Ah, I didn't notice that detail. Good idea!

I specifically used NULL_ITEM for the belts as that will include misc items (lanterns) and armour

I suppose I could add those too. Can't hurt.

Races: RACE
Groups: RACE_GROUP
Humanoid: RACE "heads male > 0"
Robot Humanoid: RACE "heads male > 0;is robot = True"
Animals: RACE "heads male == 0"
Robot Animals: RACE "heads male == 0;is robot = True"

Headgear: ARMOUR "slot=ATTACH_HAT"
Restricted Headgear: ARMOUR "slot=ATTACH_HAT;races exclude > 0"
Exclusive Headgear: ARMOUR "slot=ATTACH_HAT;races > 0"

Body: ARMOUR "slot=ATTACH_BODY"
Restricted Body: ARMOUR "slot=ATTACH_BODY;races exclude > 0"
Exclusive Body: ARMOUR "slot=ATTACH_BODY;races > 0"

Shirts: ARMOUR "slot=ATTACH_SHIRT"
Restricted Shirts: ARMOUR "slot=ATTACH_SHIRT;races exclude > 0"
Exclusive Shirts: ARMOUR "slot=ATTACH_SHIRT;races > 0"

Legs: ARMOUR "slot=ATTACH_LEGS"
Restricted Legs: ARMOUR "slot=ATTACH_LEGS;races exclude > 0"
Exclusive Legs: ARMOUR "slot=ATTACH_LEGS;races > 0"

Boots: ARMOUR "slot=ATTACH_BOOTS"
Restricted Boots: ARMOUR "slot=ATTACH_BOOTS;races exclude > 0"
Exclusive Boots: ARMOUR "slot=ATTACH_BOOTS;races > 0"

Belts: NULL_ITEM "slot=ATTACH_BELT"
Restricted Belts: NULL_ITEM "slot=ATTACH_BELT;races exclude > 0"
Exclusive Belts: NULL_ITEM "slot=ATTACH_BELT;races > 0"

I hope you don't mind me posting some changes I've done with my fcs.

@Salty Oreos You're right, it's missing the boots. Thanks for pointing it out. I'll push an update.

Doesn't contain an armour subsection for boots, I edited my layout file to include boots and it works fine. Was this accidental?

I recommend you try using this too: https://steamcommunity.com/sharedfiles/filedetails/?id=2909495250

It adds new properties and fields to stuff for even more customization

Oh wow, I've been spending the last two months working on a major overhaul and wish I tried this earlier. It is a major improvement. Thank you!