would parse each line in myfile.txt, ignoring lines that begin with a semicolon, passing the 2nd and 3rd token from each ...

would parse each line in myfile.txt, ignoring lines that begin with      a semicolon, passing the 2nd and 3rd token from each line to the for      body, with tokens delimited by commas and/or spaces.  Notice the for      body statements reference %%i to get the 2nd token, %%j to get the      3rd token, and %%k to get all remaining tokens after the 3rd.  For      file names that contain spaces, you need to quote the filenames with      double quotes.  In order to use double quotes in this manner, you also      need to use the usebackq option, otherwise the double quotes will be      interpreted as defining a literal string to parse.        %%i is explicitly declared in the for statement and the %%j and %%k      are implicitly declared via the tokens= option.  You can specify up      to 26 tokens via the tokens= line, provided it does not cause an      attempt to declare a variable higher than the letter 'z' or 'Z'.      Remember, FOR variables are single-letter, case sensitive, global,       and you can't have more than 52 total active at any one time.        You can also use the FOR /F parsing logic on an immediate string, by      making the filenameset between the parenthesis a quoted string,      using single quote characters.  It will be treated as a single line      of input from a file and parsed.        Finally, you can use the FOR /F command to parse the output of a      command.  You do this by making the filenameset between the      parenthesis a back quoted string.  It will be treated as a command      line, which is passed to a child CMD.EXE and the output is captured      into memory and parsed as if it was a file.  So the following      example:          FOR /F "usebackq delims==" %%i IN (`set`) DO @echo %%i        would enumerate the environment variable names in the current      environment.