Proposition 5.2.4 (One Sided Limits).label Let $E$ be a complete locally convex space and $f\in BV([a,b];E)$, then for each $x\in [a,b]$, the limits $\limit{y\searrow x}f(y)$ and $\limit{y\nearrow x}f(y)$ exists.
Proof. I’ll prove this whenever I reference it.$\square$