Variable DAY_MAP`Const`

DAY_MAP: Readonly<
    {
        FR: 5;
        FRI: 5;
        MO: 1;
        MON: 1;
        SA: 6;
        SAT: 6;
        SU: 7;
        SUN: 7;
        TH: 4;
        THU: 4;
        TU: 2;
        TUE: 2;
        WE: 3;
        WED: 3;
    },
> = ...

Mapping of 2-letter and 3-letter ISO day abbreviations to 1-indexed weekday numbers (1..7, Monday=1, Sunday=7).