Where a brochure, leaflet, poster etc is designed with full bleed (print right up to the edge of the document) the printer will use SR sized paper and card. SR is the abbreviation for ‘supplementary raw’. SR is larger than the A series, eg SRA4 225mm x 320mm, A4 210mm x 297mm.
The extra size is required for mechanical gripping on digital and offset printing presses.
Once a document is printed with full bleed onto a greater surface area, it is cut to size (following cut marks included in the design). It is critical that the graphic is designed with overprint so that the document can be cut back. The end result is a seamless document.