<p>Continuous rolled material (10) is described which is formed as lay flat tubing and which has lines of perforations (14) running transversely to the axis of the material and dividing the material into discrete units. Alternate lines of perforations (27) are sinusoidal lines. There are cuts (22, 24) in these lines of perforations at the mid-portions between the crests of the sinusoidal lines. The remaining perforations are arranged so that the transverse components of their lengths are substantially constant. Other kinds of perforated continuous material are also described.</p>
