Function header variables prepended with article

At Vaughn Vernon's Implementing Domain-Driven Design book, I see methods with variable names like

public Discussion startDiscussionFor(
    ForumNavigationService aForumNavigationServie,
    Author anAuthor,
    String aSubject) {
…

So, I'd like to read up a bit about the advantages and disadvantages of this style, can anybody help me whether this coding style has a particular name?