Decimal inches suggests 10 characters per inch, i.e. Pica. Pica was pretty common on US typewriters. Absent 1 and 0 keys were pretty common before the 1950’s a

Decimal inches suggests 10 characters per inch, i.e. Pica. Pica was pretty common on US typewriters. Absent 1 and 0 keys were pretty common before the 1950’s and 60’s. Particularly on portable and lower end models. $, @, and ! are often absent as well.