By accident I came across an to my knowledge undocumented feature. One of the queries contained an instruction to convert a string to a Sybase date type:
SELECT CONVERT(DATE, '.', 105)
This works as expected with values like '16-11-2017', but one of the values by accident was . (point). This resulted in the (to me) illogical result of '2017-10-31' in November, now in December the result is somehow '2017-11-30'.
What is the meaning of the point character and why is the result the last day of last month?