font behavior in calc

Good evening
I noticed this before:
I have a spreadsheet with alphanumeric items, Japanese terms, a few
"functions" and dates.

In the default style for spreadsheets as well as a private style I
defined fonts to be used
and the style, dates are displayed.
However, in particular recently, whenever I open this file, the dates,
which are supposed to be in Japanese,
suddenly use Arial (the font specified for Western text) and thus look
very queer.

When I apply the default style or my style, the date, which looks in
Japanese like
10月2に日 = Oct 2
suddenly is replaced by a number: 41914

Which does not make any sense to me and is NOT what I instructed the
computer to do.

Is there a comprehensible reason behind this behavior?
Is there any way to turn this definitely "erratic" behavior off?

Thank you.
Thomas

Good evening
I noticed this before:
I have a spreadsheet with alphanumeric items, Japanese terms, a few
"functions" and dates.

In the default style for spreadsheets as well as a private style I
defined fonts to be used
and the style, dates are displayed.
However, in particular recently, whenever I open this file, the dates,
which are supposed to be in Japanese,
suddenly use Arial (the font specified for Western text) and thus look
very queer.

When I apply the default style or my style, the date, which looks in
Japanese like
10月2に日 = Oct 2
suddenly is replaced by a number: 41914

Which does not make any sense to me and is NOT what I instructed the
computer to do.

Is there a comprehensible reason behind this behavior?
Is there any way to turn this definitely "erratic" behavior off?

This is not strictly erratic behaviour: you will find that 41914 is the
number of days since 1.1.1900, which is the starting point for date
caclucations. You must ensure that your cell is formatted for the kind
of date you want to see.

Cheers
Harvey