yyyy'-'MM'-'dd'T'HH':'mm':'ss - What is the meaning of 'T' here?

What is the meaning of T in this datetime pattern ?

yyyy'-'MM'-'dd'T'HH':'mm':'ss 2011-06-14T04:12:36

What is SSSZ in date format?

Dates are formatted using the following format: "yyyy-MM-dd'T'hh:mm:ss'Z'" if in UTC or "yyyy-MM-dd'T'hh:mm:ss[+|-]hh:mm" otherwise. On the contrary to the time zone, by default the number of milliseconds is not displayed. However, when displayed, the format is: "yyyy-MM-dd'T'hh:mm:ss.

What is the difference between HH mm SS and HH mm SS?

[h]:mm:ss shows the total number of hours, even if the number of hours is 24 or more. hh:mm:ss effectively only shows the excess hours over and above complete multiples of 24. In your example, 105 hours is 4x24, or 4 whole days, plus 9 more hours, so it just shows the 9.

It just shows the start of the Time component in a standard ISO 8601 date time string. Wikipedia has a detailed page about this standard format.