UNDERSTAND this part of string

[sal21]

;2014-10-03-09.42.46.508536;

this is a part of csv.
the head of records is named DATE_OP.
i understand the first two block is the date and hour but the 3th block(508536)?

note:
I think the csv is created from a CICS.

[HansV]

As far as I can tell, it means the 3rd of October 2013, at 09:42:46 plus 0,508536 seconds.