The invention relates to a method for handling, namely forwarding and extracting, data, especially messages, in a system comprising at least one data source and a plurality of data receivers. The variable slit width device includes a pair of freely rotatable rotary parts for pressing inclined guide parts of a pair of slit holders, pressing parts for supporting the pair of rotary parts, and linear guides having guide parts formed at the lower surfaces thereof and extending horizontally in a direction crossing with guide rails at right angles. The compensation mask includes one or more non-defective second defined masks each having a pattern configuration to be formed in a defective among said first defined masks. When the tarpaulins are fully extended along the sides of the trailer section, the tarpaulins effectively aid in preventing the birds from being buffeted about by excessive wind as the coop trailer travels along the roads. The second regulator is in selective electrical communication with the exciter through a second line conductor having second separable contacts such that an output of the second regulator may be selectively provided as an input to the exciter.