Given the task definition and input, reply with output. This task is about reading the given passage and construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) its answer is a continuous text span from the paragraph. Avoid creating questions that (i) can be answered correctly without actually understanding the paragraph and (ii) uses same words or phrases given in the passage.

In Dutch itself, Diets went out of common use - although Platdiets is still used for the transitional Limburgish-Ripuarian dialects in the north-east of Belgium. Nederlands, the official Dutch word for "Dutch", did not become firmly established until the 19th century. This designation had been in use as far back as the end of the 15th century, but received competition from the more popular terminology Nederduits, "Low Dutch", for several reasons. One of them was it reflected a distinction with Hoogduits, "High Dutch", meaning the language spoken in Germany. The Hoog was later dropped, and thus, Duits narrowed down in meaning to refer to the German language.
Dutch people didn't have an officially established word for the "Dutch" language until what century?