A line in art is defined as a point moving in space, and it’s one of the seven elements of art (line, color, shape, form, texture, value, space). It is one of the most crucial elements, as everything begins with just a simple dot in space, that transforms into lines and then drawings. Bar line These separate measures (see time signatures below for an explanation of measures).Also used for changes in time signature.Bar lines are extended to connect multiple staves in certain types of music, such as for keyboard or harp, and in conductor scores, but such extensions are not used for other types of music, such as vocal scores. Line Integrals of Vector Fields. Fundamental Theorem for Line Integrals. This second form is often how we are given equations of planes. If the line is parallel to the plane then any vector parallel to the line will be orthogonal to the normal vector of the plane.