Are shields armour? Can they be enhanced with potency runes?

[Arivia]

The Rulebook is indistinct on this, so I wanted to ask. Are shields technically armour? Can they be enhanced by armour potency runes for example?

My guess is that they can't be, because a +5 shield would be absurd math-wise, and because there are level 18 item shields that do not list any potency. But it's good to be sure.

[Fuzzy-Wuzzy]

Nope. Shields are their own thing. No potency runes, no property runes. (On the shield itself that is---you can put them on an attached shield boss or whatever.)

[JDLPF]

Playtest Rulebook, p. 379 wrote:

SHIELDS

Unlike magic armor, magic shields can’t be etched with runes granting potency or properties. All magic shields are specific items with a wide variety of protective effects, as described in their entries.

[Cantriped]

Shields are armor; or rather a subtype of armor, like light armor is. It just so happens to make exception to nearly every single rule related to armor... for reasons.
The above posters are correct regarding the important bit though: Shields can only carry specific enchantments like Sturdy.