Another method would be to plan a continuous flowing line with forms branching out on one side or on both. [Figs. 18 and 19] are border designs, for which purpose this arrangement is often used, though it can also well form an all-over pattern; sometimes these lines used over a surface are made to cross each other, tartan wise, by running in two directions, producing an apparently complicated design by very simple means.
Designs may be planned on the counterchange principle. This is a system of mass designing that involves the problem of making a pattern out of one shape, continually repeated, and fitting into itself in such a way as to leave no interstices. The simplest example of this is to be found in the chess board, and it will easily be seen that a great number of shapes might be used instead of the square. [Fig. 20] is an example of a counterchange design carried out in inlay; for this method of work counterchange is very suitable. On reference to the chapter upon this work another example will be found ([page 181]). [Fig. 21] illustrates the same principle, further complicated by the repetition of the form in three directions instead of in two only.
A method of further enriching a straightforward pattern, covering a plain surface, is to work a subsidiary pattern upon the background. This is usually of a monotonous and formal character in order not to clash with the primary decoration, though this relationship may sometimes be found reversed. It has the appearance of being some decoration belonging to the ground rather than to the primary pattern; in its simplest form it appears as a mere repeating dot or a lattice (see [fig. 22]), but it may be so elaborated as to cover with an intricate design every portion of the exposed ground not decorated with the main pattern.