The Warforged race from the initial version of Wayfinder's Guide to Eberron (which matches the version in UA: Eberron Races) has a unique feature, Integrated Protection, that affects their armor class (AC) and ability to wear armor, detailed below:
Your body has built-in defensive layers, which determine your armor class. You gain no benefit from wearing armor, but if you are using a shield, you apply its bonus as normal.
You can alter your body to enter different defensive modes; each time you finish a long rest, choose one mode to adopt from the Integrated Protection table, provided you meet the mode's prerequisite.
Integrated Protection
Mode Prerequisite Armor Class Darkwood core (unarmored) None 11 + your Dexterity modifier (add proficiency bonus if proficient with light armor) Composite plating (armor) Medium armor proficiency 13 + your Dexterity modifier (maximum of 2) + your proficiency bonus Heavy plating (armor) Heavy armor proficiency 16 + your proficiency bonus; disadvantage on Dexterity (Stealth) checks
Nowhere in this description does it say anything about the "built-in defensive layers" counting as armor for the purposes of wearing armor, but this is heavily implied by the table's parenthetical descriptions following each mode, such as the medium mode Composite Plating (armor).
This is important in a number of cases, such as the Defense fighting style fighters can take at 1st level and paladins can take at 2nd level (PHB p. 72, 84; emphasis mine):
While you are wearing armor, you gain a +1 bonus to AC.
and the Rage feature that barbarians receive at 1st level (PHB, p. 48; emphasis mine):
In battle, you fight with primal ferocity. On your turn, you can enter a rage as a bonus action.
While raging, you gain the following benefits if you aren't wearing heavy armor: […]
Is the feature text more authoritative, not specifying the Integrated Protection as armor worn?
Or is the table with its parenthetical descriptions more authoritative, meaning that the second and third options count as wearing armor for the above features?
Best Answer
Composite Plating and Heavy Plating are intended to count as armor.
Keith Baker, original creator of Eberron and lead designer for the Wayfinder's Guide to Eberron, addresses this question (and many others) in the WGtE FAQ on his website:
Baker points out that the feature doesn't specifically clarify that Composite Plating or Heavy Plating count as armor - but the parenthetical after each one reflects the intent, which is that Darkwood Core counts as being unarmored and that the other two options count as being armored. This is relevant for features like the Defense fighting style (which requires you to be armored), or the monk's Unarmored Movement feature (which, as the name implies, requires that you be unarmored).
In another response, he also says:
So you can choose which of the three modes to use (depending on what armor you're proficient in), but you can't choose whether that mode counts as being armored.
...but as currently written, they don't count specifically as medium or heavy armor.
Baker also answers a related question about what kind of armor the Integrated Protection feature counts as:
This may change in the future, but as of right now, a warforged barbarian can gain the benefits of Rage regardless of what defensive mode they're in. However, they can't benefit from features that forbid any armor at all while using Composite Plating or Heavy Plating.