What does the Black shield icon mean for clan war availability?

Question

• Green shield = opted in
• red shield = opted out
• black shield = ?

What does the black shield mean? Are they in a war in another clan?

Answer 1

the Small Shield in one's profile and in the list of clan members comes in 3 states,

• Red - the player has Opt-Out of Clan Wars regardless of Trophy Count
• Green - the player as Opt-In of Clan Wars
• Black - the player is ineligible for Clan Wars

While I have never seen the Black Shield in my own profile, when I have seen it with other members it has normally been for new members who had came from another clan. there is also a small bar under the Black Shield which is how long that person still has to wait before they can choose to Opt-In/Out of clan wars.

Should Note that a Clan Leader can override a player's Clan War Prference

Note: Leaders can still choose players that have chosen to opt-out by default, and can always leave out players that have chosen to opt-in by default.

Source: Clan Wars - Eligiblity of Members Point 2

Answer 2

Black means they are a part of a war in another clan and as we know we cannot be in two wars at a time so the player is not eligible for war in any other clan he joins. They can join next war only if the time of current war they are a part of ends.

http://clashofclans.wikia.com/wiki/Clan_Wars

Eligibility of Members

Members are also not eligible for a war if they have left a clan with the member currently participating in a war; this status remains until that clan finishes their war (e.g. if Player A leaves Clan A that is currently in war with 1 day left and joins Clan B, Player A will not be eligible in Clan B's wars until 1 day has passed).

Answer 3

Black means they are new to the clan and aren't eligible for wars yet.
They will be eligible by the time your next war starts.

Answer 4

Black means they came from another clan and started a war then left, they will be eligible for war once the other clan they came from is done with war.