GGU-SLICE: "Page size and margins" menu item
The default page set-up is A4 when the program is started. You can edit the page format in the following dialog box.

"Page in general" defines the size of the output sheet. The A4 format is set as default. The program automatically draws thin cutting borders around the page, which are required when using a plotter on paper rolls. The borders can be switched off using the "With borders" menu item.
"Page margin" defines the position of a frame as a distance to the margins. This frame encloses the subsequent diagram.
In order to achieve 1:1 output on an A4 printer the borders must be switched off and the page height and page borders be adapted to the printable area of the printer.