This is a better explanation of the pattern, "0bw" whose job it is to position the cursor at the first character of an argument such as a boolean condition or subroutine name and just entered on its own line. 

"0bw" prefixes several macros while doing the job of a sub-macro. On the one hand for cases when the argument is indented by some amount, then "0w" would accomplish the same thing.  

If on the other hand there is no whitespace between the left margin and the argument, a "0w" would result in positioning the cursor to the beginning of the next word after the argument.  To fix that, the 'b' in "0bw" moves the cursor to the start of the word before the argument, guaranteeing the 'w' to move to the beginning of the argument.  

Applying "0bw" to the case with indention, the cursor merely skips all the whitespace before the argument during the 'w' move and therefore also winds up at the start of the argument, as desired and therefore works for both cases.