>>>
Now the more sophisticated systems -
of which the British ICT (ICL) was one
- used an offset to hold dates.? The ICL 1900 range? used a technique of
holding the number of days since the Jan 1st 1900
<<<<
Except that they made a minor blunder ...
Originally it had been defined that Day 0 was Jan 1st 1900
Then - after lots of such dates were "in the field" - someone discovered
that 1900 was not a leap year. (probably the first well-informed person to
write their own date-conversion routine who wondered why their code produced
different results from the system standard)
The only reasonable solution was to redefine Jan 1st 1900 as Day 1 so all
dates from Mar 1st 1900 onwards remained unchanged.
Andy