!! used as default html header if there is none in the selected theme.
There are 4 ways to describe a general line (not passing through the origine, neigher vertical nor horizontal) in the cartesian plane: by an implicite equation, an equation giving y as a function of x, one giving x as a function of y, or a system of parametric equations.
Please take note that WIMS pages are interactively generated; they are not ordinary HTML files. They must be used interactively ONLINE. It is useless for you to gather them through a robot program.