# Mixed Hodge structures over $F\otimes \mathbb{R}$

Let $$F$$ be a number field. Nekovàř, on page 18 of Values of L-functions and p-adic cohomology, is referring to the category of mixed Hodge structures over $$F\otimes_{\mathbb{Q}} \mathbb{R}$$. Can anyone precise the definition of the above?

Many thanks!