Which allele combination represents a female who is a carrier for an X-linked recessive disorder?

A female has two X chromosomes. If the disease is an X-linked recessive disorder, and the female does not have the disease, but is a carrier of the disease, then it will contain only one X-linked recessive allele for the disorder.

Let the allele for X-linked recessive disorder be : Xr

Then the genetic combination will be

XXr