The Armanen row is an early twentieth-century construction by Guido von List, published in 1908. Every one of its eighteen characters can be described by what it was before he took it and what he did to it.
The character behind it
Rit corresponds to the Younger Futhark character whose Old Norse name was reid, meaning riding or a ride, and which the rune poems gloss with horses and journeys. The character is common in the Viking-age inscriptional record, where it does ordinary work as the letter R.
What von List did with it
He kept the sound value, Germanised the name to Rit, and gave the character a meaning belonging to his own scheme rather than to the rune poems. Sixteen of his eighteen map onto Younger Futhark characters in this way; the last two, Eh and Gibor, do not exist in that row and were supplied to reach the count of eighteen.
Why eighteen
Von List set the number to match the eighteen rune-charms listed in the Havamal in the Poetic Edda. The Havamal does not describe an alphabet of eighteen characters, and no historical futhark has eighteen. The correspondence is his, not the tradition's.
Reception
The Armanen row was taken up in volkisch circles and, in the 1930s and 1940s, by National Socialist organisations. This atlas records that history plainly and does not present the row as Germanic antiquity.