# What does this sign mean in the definition of triangulated categories?

I have two questions about Wikipedia's definition of triangulated categories.

1. One of the axioms for distinguished triangles (TR 2) says that if $X\overset u\to Y \overset v\to Z \overset w\to X$ is a distinguished triangle, then so are $Y \overset v\to Z \overset w\to X \overset{-u}\longrightarrow Y$ and $Z[-1]\overset{-w[-1]}\longrightarrow X \overset u\to Y \overset v \to Z$. I get that the translation functor defines $u$ and $w[-1]$, but what does the minus sign in $-u$ and $-w[-1]$ mean?

2. In TR 1, what does the final "$\to \cdot$" mean? Is it the same as a final "$\to$" as used in the definition of a triangle three lines further up?

Question 2 is really just a PS (I assume that the answer is an affirmative, because what else could it be?). It's question 1 that has me wondering.

In a triangulated category, the morphism sets are actually vector spaces over a base field (or modules over a base ring, depending on your level of generality). Hence $-u$ is the morphism $u$ multiplied by the scalar $-1$.
As for your second question, the arrow is what you expect in a triangle. If you wish to be precise, you could write $X\to X\to 0 \to X$.