# 04: Name a Ziel

**What to build:** The person types one Koordinate as Gitter, Rechtswert, and Hochwert. The Gitter starts as `32U MA`. A valid Ziel is shown in red and the view centers on it at 1:25,000, even while its Kacheln are blank. A bad Koordinate, or one that no Blatt covers, is explained in German and leaves the previous Ziel and the view unchanged. A second Koordinate replaces the first. The Ziel is gone after the page is left.

**Blocked by:** 01: Open the Karte

**Status:** done

- [x] The entry is three fields labelled Gitter, Rechtswert, and Hochwert, and Gitter starts as `32U MA`.
- [x] `32u ma` and `32UMA` are accepted as the same Gitter as `32U MA`.
- [x] Rechtswert and Hochwert must be exactly five digits. Any other length is rejected with a German explanation.
- [x] An impossible Gitter is rejected with a German explanation.
- [x] A rejected Koordinate leaves the previous Ziel and the view unchanged.
- [x] A Koordinate that no Blatt covers, including a hole between Blätter, is rejected and leaves the previous Ziel and the view unchanged.
- [x] A valid Ziel is drawn in red and the view centers on it at 1:25,000, even when its Kacheln are still blank.
- [x] The typed Gitter, Rechtswert, and Hochwert stay visible after a successful entry.
- [x] Entering another Koordinate replaces the Ziel. There is only one Ziel.
- [x] The Koordinate is decoded on the device, with no network required.
- [x] Leaving or reloading the page drops the Ziel. It is not stored.

## Comments

The screen offers Gitter, Rechtswert, and Hochwert, starting at `32U MA`. A valid Ziel is red and centers the view at 1:25,000. A rejected Koordinate leaves the previous Ziel. A new session does not keep the Ziel.