We are studying the Diophantine exponent μ
n,l defined for integers 1≤
l<
n and a vector α∈ℝ
n by letting
where
is the scalar product,
denotes the distance to the nearest integer and
is the generalised cone consisting of all vectors with the height attained among the first
l coordinates. We show that the exponent takes all values in the interval [
l+1,∞), with the value
n attained for almost all α. We calculate the Hausdorff dimension of the set of vectors α with μ
n,l (α)=μ for μ≥
n. Finally, letting
w n denote the exponent obtained by removing the restrictions on
, we show that there are vectors α for which the gaps in the increasing sequence μ
n,1(α)≤...≤μ
n,n-1(α)≤
w n (α) can be chosen to be arbitrary.