Anchoring in a regex

[Robert Hicks]

syn match tclV "ttk\(\(::\)\?\([[:alnum:]_.]*::\)*\)\a[a-zA-Z0-9_.]*"
I only want this to work "ttk" at the start. I know that ^ means the 
start but I am not sure how to add that (I did try just adding it) to 
make the regex start with "ttk".

Robert