The processing of 2-digit year by oracle

If the database date format is set to dd-mon-yy, then this yy specifically indicates that year, for example: is the last 13 of 12-12-13 2013 or 1913 or something? This has something to do with the current date. Yy says that when the two-digit year is in the format of the year, it specifically indicates which year and the current date are in a century, if this year is 2014, then the specific date is December 12, 2013. if this year is 1999, then 12-12-13 means December 12, 1913.

If the year in the date is formatted as RR, the specific year of the date is determined by the two parts; the two digits of the year provided, the last two digits of the current date year. The rules are as follows:

Note: the text content of the picture blocked is: the first two digits of RR use the first two digits of the current year-1

Remember that on the left are the last two digits of the current year, above is RR, and then remember the positions of 1, 2, 3, 4, 1 and 4 are the same as the current year, 2-1 min 3 + 1