Before revision: In the case of a 1st-order pyramidal plane trace, the slip could be in either 〈 𝑎 〉 or 〈 𝑐 + 𝑎 〉 directions; slip trace analysis cannot discriminate between these.
After revision: In the case of a 1st-order pyramidal plane trace, the slip could be in either langle; 𝑎 rangle; or 𝑐 + 𝑎 rangle;langle; directions; slip trace analysis cannot discriminate between these.