asterisk allowed for list items

[c . buhtz]

I was looking into https://orgmode.org/worg/dev/org-syntax.html#Items to 
find out which characters are allowed as "bullets" for unorderd lists.
I cite from there
"An asterisk, hyphen, or plus sign character (i.e., *, -, or +)."

I wonder why * is allowed because * also starts a heading. So how does a 
piece of software/parser decide if a line starting with an * is a 
heading or a list item?