dateitems day-of-week disjunction

[Ben Rubinstein]

The dictionary says that the seventh item of dateitems is
>  the numeric day of the week where Monday is day 1, Tuesday is day 2, and so forth

When I try this I find that today, Wednesday, the seventh item is 4.  If I 
change the date to Sunday, it's 1.

(Both docs and behaviour are consistent with 6.7.11 or 8.1.3 (rc 1) or 
versions in between.)

Is this an error in the documentation, or an error in the code (in which case 
too long standing to change, so it might as well be treated as an error in the 
docs); or is it due to some setting somewhere?

TIA.

Ben