What does :: (double colon) mean in DOS batch files?

Question

I found this program http://baiyunmanor.com/blog/work/get-current-date-time-in-dos-batch-file/

But I don't know what does the line

:: datetime.bat

at the end mean?

Answer 1

:: is a label (also, inaccurately, known in the wild by comment label) can be, in practice, considered a comment just as REM is, as it is an "un-goto-able" label.

There are some differences between REM and ::, though. The main ones are:

• With ECHO ON a REM line is shown but not a line commented with ::

• A :: can execute a line end caret (that is, a ^ at the end of a line starting with :: makes the next line also a comment):

  :: This is a comment^
  echo but watch out because this line is a comment too
  

• Labels and :: have a special logic and can cause problems in parentheses blocks - take care when using them inside ( ). Example:

  for %%D in (hi) do (
      echo Before...
      :: My comment
      :: Some other comment
      echo After...
  )
  

  Outputs:

  Before ...
  The system cannot find the drive specified.
  After...