What do device formats (SPAD->Device Format) do?

They contain comands that are used to set features like font, font size, character set, orientation, margins, and vertical/horizontal spacing. If you are using SAPWIN, some common commands are:

• \e%SAPWIN%: change to SAPWIN command set
• \eWxxx;: change to character set xxx
• \eFFONTNAME;: set to font FONTNAME
• \ePP;: set to orientation P (Portrait)
• \eSxxxX: set fontsize to zzz (where 200 = 10.0 pt, 240 = 12.0 pt)
• \elx;: set vertical spacing to x lines per inch
• \ecxx.y;: set horizontal spacing to xx.y (e.g. 12.0) chars per inch
• \eMTxxx;: set top margin to xxx (where 567 = 1.0cm)
• \eMLxxx;: set left margin to xxx (where 567 = 1.0cm)